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Signed eight-bit values

Set 8 of 8 · 32 worked questions. Predict your result before expanding the solution.

These worked traces are meant to build fluency through controlled variation. If several answers feel identical, try the next difficult value and look for the point where a carry, sign, branch, or selected memory address changes the outcome.

Foundations · Problem 0225

Interpret 11100000 as an 8-bit two’s complement value.

Try it on paper first. The worked answer is hidden below.

Reveal detailed solution →
  1. Treat 11100000 as exactly eight bits.
  2. For signed 8-bit values the leftmost column has weight −128, not +128.
  3. The remaining seven columns have weights 64, 32, 16, 8, 4, 2 and 1.
  4. The leading sign bit is 1, so its signed contribution is -128.
  5. The lower seven bits contribute 96.
  6. Add those contributions: -128 + 96 = -32.
  7. As an unsigned pattern, the same eight bits represent 224.
  8. The signed range for eight bits is −128 through +127.
  9. Bitwise inversion alone yields 00011111; inversion plus one wraps modulo 256.
  10. The eight-bit negated pattern is 00100000.
  11. Answer: signed(11100000) = -32.

Final answer: -32

Foundations · Problem 0226

Interpret 11100001 as an 8-bit two’s complement value.

Try it on paper first. The worked answer is hidden below.

Reveal detailed solution →
  1. Treat 11100001 as exactly eight bits.
  2. For signed 8-bit values the leftmost column has weight −128, not +128.
  3. The remaining seven columns have weights 64, 32, 16, 8, 4, 2 and 1.
  4. The leading sign bit is 1, so its signed contribution is -128.
  5. The lower seven bits contribute 97.
  6. Add those contributions: -128 + 97 = -31.
  7. As an unsigned pattern, the same eight bits represent 225.
  8. The signed range for eight bits is −128 through +127.
  9. Bitwise inversion alone yields 00011110; inversion plus one wraps modulo 256.
  10. The eight-bit negated pattern is 00011111.
  11. Answer: signed(11100001) = -31.

Final answer: -31

Foundations · Problem 0227

Interpret 11100010 as an 8-bit two’s complement value.

Try it on paper first. The worked answer is hidden below.

Reveal detailed solution →
  1. Treat 11100010 as exactly eight bits.
  2. For signed 8-bit values the leftmost column has weight −128, not +128.
  3. The remaining seven columns have weights 64, 32, 16, 8, 4, 2 and 1.
  4. The leading sign bit is 1, so its signed contribution is -128.
  5. The lower seven bits contribute 98.
  6. Add those contributions: -128 + 98 = -30.
  7. As an unsigned pattern, the same eight bits represent 226.
  8. The signed range for eight bits is −128 through +127.
  9. Bitwise inversion alone yields 00011101; inversion plus one wraps modulo 256.
  10. The eight-bit negated pattern is 00011110.
  11. Answer: signed(11100010) = -30.

Final answer: -30

Foundations · Problem 0228

Interpret 11100011 as an 8-bit two’s complement value.

Try it on paper first. The worked answer is hidden below.

Reveal detailed solution →
  1. Treat 11100011 as exactly eight bits.
  2. For signed 8-bit values the leftmost column has weight −128, not +128.
  3. The remaining seven columns have weights 64, 32, 16, 8, 4, 2 and 1.
  4. The leading sign bit is 1, so its signed contribution is -128.
  5. The lower seven bits contribute 99.
  6. Add those contributions: -128 + 99 = -29.
  7. As an unsigned pattern, the same eight bits represent 227.
  8. The signed range for eight bits is −128 through +127.
  9. Bitwise inversion alone yields 00011100; inversion plus one wraps modulo 256.
  10. The eight-bit negated pattern is 00011101.
  11. Answer: signed(11100011) = -29.

Final answer: -29

Foundations · Problem 0229

Interpret 11100100 as an 8-bit two’s complement value.

Try it on paper first. The worked answer is hidden below.

Reveal detailed solution →
  1. Treat 11100100 as exactly eight bits.
  2. For signed 8-bit values the leftmost column has weight −128, not +128.
  3. The remaining seven columns have weights 64, 32, 16, 8, 4, 2 and 1.
  4. The leading sign bit is 1, so its signed contribution is -128.
  5. The lower seven bits contribute 100.
  6. Add those contributions: -128 + 100 = -28.
  7. As an unsigned pattern, the same eight bits represent 228.
  8. The signed range for eight bits is −128 through +127.
  9. Bitwise inversion alone yields 00011011; inversion plus one wraps modulo 256.
  10. The eight-bit negated pattern is 00011100.
  11. Answer: signed(11100100) = -28.

Final answer: -28

Foundations · Problem 0230

Interpret 11100101 as an 8-bit two’s complement value.

Try it on paper first. The worked answer is hidden below.

Reveal detailed solution →
  1. Treat 11100101 as exactly eight bits.
  2. For signed 8-bit values the leftmost column has weight −128, not +128.
  3. The remaining seven columns have weights 64, 32, 16, 8, 4, 2 and 1.
  4. The leading sign bit is 1, so its signed contribution is -128.
  5. The lower seven bits contribute 101.
  6. Add those contributions: -128 + 101 = -27.
  7. As an unsigned pattern, the same eight bits represent 229.
  8. The signed range for eight bits is −128 through +127.
  9. Bitwise inversion alone yields 00011010; inversion plus one wraps modulo 256.
  10. The eight-bit negated pattern is 00011011.
  11. Answer: signed(11100101) = -27.

Final answer: -27

Foundations · Problem 0231

Interpret 11100110 as an 8-bit two’s complement value.

Try it on paper first. The worked answer is hidden below.

Reveal detailed solution →
  1. Treat 11100110 as exactly eight bits.
  2. For signed 8-bit values the leftmost column has weight −128, not +128.
  3. The remaining seven columns have weights 64, 32, 16, 8, 4, 2 and 1.
  4. The leading sign bit is 1, so its signed contribution is -128.
  5. The lower seven bits contribute 102.
  6. Add those contributions: -128 + 102 = -26.
  7. As an unsigned pattern, the same eight bits represent 230.
  8. The signed range for eight bits is −128 through +127.
  9. Bitwise inversion alone yields 00011001; inversion plus one wraps modulo 256.
  10. The eight-bit negated pattern is 00011010.
  11. Answer: signed(11100110) = -26.

Final answer: -26

Foundations · Problem 0232

Interpret 11100111 as an 8-bit two’s complement value.

Try it on paper first. The worked answer is hidden below.

Reveal detailed solution →
  1. Treat 11100111 as exactly eight bits.
  2. For signed 8-bit values the leftmost column has weight −128, not +128.
  3. The remaining seven columns have weights 64, 32, 16, 8, 4, 2 and 1.
  4. The leading sign bit is 1, so its signed contribution is -128.
  5. The lower seven bits contribute 103.
  6. Add those contributions: -128 + 103 = -25.
  7. As an unsigned pattern, the same eight bits represent 231.
  8. The signed range for eight bits is −128 through +127.
  9. Bitwise inversion alone yields 00011000; inversion plus one wraps modulo 256.
  10. The eight-bit negated pattern is 00011001.
  11. Answer: signed(11100111) = -25.

Final answer: -25

Foundations · Problem 0233

Interpret 11101000 as an 8-bit two’s complement value.

Try it on paper first. The worked answer is hidden below.

Reveal detailed solution →
  1. Treat 11101000 as exactly eight bits.
  2. For signed 8-bit values the leftmost column has weight −128, not +128.
  3. The remaining seven columns have weights 64, 32, 16, 8, 4, 2 and 1.
  4. The leading sign bit is 1, so its signed contribution is -128.
  5. The lower seven bits contribute 104.
  6. Add those contributions: -128 + 104 = -24.
  7. As an unsigned pattern, the same eight bits represent 232.
  8. The signed range for eight bits is −128 through +127.
  9. Bitwise inversion alone yields 00010111; inversion plus one wraps modulo 256.
  10. The eight-bit negated pattern is 00011000.
  11. Answer: signed(11101000) = -24.

Final answer: -24

Foundations · Problem 0234

Interpret 11101001 as an 8-bit two’s complement value.

Try it on paper first. The worked answer is hidden below.

Reveal detailed solution →
  1. Treat 11101001 as exactly eight bits.
  2. For signed 8-bit values the leftmost column has weight −128, not +128.
  3. The remaining seven columns have weights 64, 32, 16, 8, 4, 2 and 1.
  4. The leading sign bit is 1, so its signed contribution is -128.
  5. The lower seven bits contribute 105.
  6. Add those contributions: -128 + 105 = -23.
  7. As an unsigned pattern, the same eight bits represent 233.
  8. The signed range for eight bits is −128 through +127.
  9. Bitwise inversion alone yields 00010110; inversion plus one wraps modulo 256.
  10. The eight-bit negated pattern is 00010111.
  11. Answer: signed(11101001) = -23.

Final answer: -23

Foundations · Problem 0235

Interpret 11101010 as an 8-bit two’s complement value.

Try it on paper first. The worked answer is hidden below.

Reveal detailed solution →
  1. Treat 11101010 as exactly eight bits.
  2. For signed 8-bit values the leftmost column has weight −128, not +128.
  3. The remaining seven columns have weights 64, 32, 16, 8, 4, 2 and 1.
  4. The leading sign bit is 1, so its signed contribution is -128.
  5. The lower seven bits contribute 106.
  6. Add those contributions: -128 + 106 = -22.
  7. As an unsigned pattern, the same eight bits represent 234.
  8. The signed range for eight bits is −128 through +127.
  9. Bitwise inversion alone yields 00010101; inversion plus one wraps modulo 256.
  10. The eight-bit negated pattern is 00010110.
  11. Answer: signed(11101010) = -22.

Final answer: -22

Foundations · Problem 0236

Interpret 11101011 as an 8-bit two’s complement value.

Try it on paper first. The worked answer is hidden below.

Reveal detailed solution →
  1. Treat 11101011 as exactly eight bits.
  2. For signed 8-bit values the leftmost column has weight −128, not +128.
  3. The remaining seven columns have weights 64, 32, 16, 8, 4, 2 and 1.
  4. The leading sign bit is 1, so its signed contribution is -128.
  5. The lower seven bits contribute 107.
  6. Add those contributions: -128 + 107 = -21.
  7. As an unsigned pattern, the same eight bits represent 235.
  8. The signed range for eight bits is −128 through +127.
  9. Bitwise inversion alone yields 00010100; inversion plus one wraps modulo 256.
  10. The eight-bit negated pattern is 00010101.
  11. Answer: signed(11101011) = -21.

Final answer: -21

Foundations · Problem 0237

Interpret 11101100 as an 8-bit two’s complement value.

Try it on paper first. The worked answer is hidden below.

Reveal detailed solution →
  1. Treat 11101100 as exactly eight bits.
  2. For signed 8-bit values the leftmost column has weight −128, not +128.
  3. The remaining seven columns have weights 64, 32, 16, 8, 4, 2 and 1.
  4. The leading sign bit is 1, so its signed contribution is -128.
  5. The lower seven bits contribute 108.
  6. Add those contributions: -128 + 108 = -20.
  7. As an unsigned pattern, the same eight bits represent 236.
  8. The signed range for eight bits is −128 through +127.
  9. Bitwise inversion alone yields 00010011; inversion plus one wraps modulo 256.
  10. The eight-bit negated pattern is 00010100.
  11. Answer: signed(11101100) = -20.

Final answer: -20

Foundations · Problem 0238

Interpret 11101101 as an 8-bit two’s complement value.

Try it on paper first. The worked answer is hidden below.

Reveal detailed solution →
  1. Treat 11101101 as exactly eight bits.
  2. For signed 8-bit values the leftmost column has weight −128, not +128.
  3. The remaining seven columns have weights 64, 32, 16, 8, 4, 2 and 1.
  4. The leading sign bit is 1, so its signed contribution is -128.
  5. The lower seven bits contribute 109.
  6. Add those contributions: -128 + 109 = -19.
  7. As an unsigned pattern, the same eight bits represent 237.
  8. The signed range for eight bits is −128 through +127.
  9. Bitwise inversion alone yields 00010010; inversion plus one wraps modulo 256.
  10. The eight-bit negated pattern is 00010011.
  11. Answer: signed(11101101) = -19.

Final answer: -19

Foundations · Problem 0239

Interpret 11101110 as an 8-bit two’s complement value.

Try it on paper first. The worked answer is hidden below.

Reveal detailed solution →
  1. Treat 11101110 as exactly eight bits.
  2. For signed 8-bit values the leftmost column has weight −128, not +128.
  3. The remaining seven columns have weights 64, 32, 16, 8, 4, 2 and 1.
  4. The leading sign bit is 1, so its signed contribution is -128.
  5. The lower seven bits contribute 110.
  6. Add those contributions: -128 + 110 = -18.
  7. As an unsigned pattern, the same eight bits represent 238.
  8. The signed range for eight bits is −128 through +127.
  9. Bitwise inversion alone yields 00010001; inversion plus one wraps modulo 256.
  10. The eight-bit negated pattern is 00010010.
  11. Answer: signed(11101110) = -18.

Final answer: -18

Foundations · Problem 0240

Interpret 11101111 as an 8-bit two’s complement value.

Try it on paper first. The worked answer is hidden below.

Reveal detailed solution →
  1. Treat 11101111 as exactly eight bits.
  2. For signed 8-bit values the leftmost column has weight −128, not +128.
  3. The remaining seven columns have weights 64, 32, 16, 8, 4, 2 and 1.
  4. The leading sign bit is 1, so its signed contribution is -128.
  5. The lower seven bits contribute 111.
  6. Add those contributions: -128 + 111 = -17.
  7. As an unsigned pattern, the same eight bits represent 239.
  8. The signed range for eight bits is −128 through +127.
  9. Bitwise inversion alone yields 00010000; inversion plus one wraps modulo 256.
  10. The eight-bit negated pattern is 00010001.
  11. Answer: signed(11101111) = -17.

Final answer: -17

Foundations · Problem 0241

Interpret 11110000 as an 8-bit two’s complement value.

Try it on paper first. The worked answer is hidden below.

Reveal detailed solution →
  1. Treat 11110000 as exactly eight bits.
  2. For signed 8-bit values the leftmost column has weight −128, not +128.
  3. The remaining seven columns have weights 64, 32, 16, 8, 4, 2 and 1.
  4. The leading sign bit is 1, so its signed contribution is -128.
  5. The lower seven bits contribute 112.
  6. Add those contributions: -128 + 112 = -16.
  7. As an unsigned pattern, the same eight bits represent 240.
  8. The signed range for eight bits is −128 through +127.
  9. Bitwise inversion alone yields 00001111; inversion plus one wraps modulo 256.
  10. The eight-bit negated pattern is 00010000.
  11. Answer: signed(11110000) = -16.

Final answer: -16

Foundations · Problem 0242

Interpret 11110001 as an 8-bit two’s complement value.

Try it on paper first. The worked answer is hidden below.

Reveal detailed solution →
  1. Treat 11110001 as exactly eight bits.
  2. For signed 8-bit values the leftmost column has weight −128, not +128.
  3. The remaining seven columns have weights 64, 32, 16, 8, 4, 2 and 1.
  4. The leading sign bit is 1, so its signed contribution is -128.
  5. The lower seven bits contribute 113.
  6. Add those contributions: -128 + 113 = -15.
  7. As an unsigned pattern, the same eight bits represent 241.
  8. The signed range for eight bits is −128 through +127.
  9. Bitwise inversion alone yields 00001110; inversion plus one wraps modulo 256.
  10. The eight-bit negated pattern is 00001111.
  11. Answer: signed(11110001) = -15.

Final answer: -15

Foundations · Problem 0243

Interpret 11110010 as an 8-bit two’s complement value.

Try it on paper first. The worked answer is hidden below.

Reveal detailed solution →
  1. Treat 11110010 as exactly eight bits.
  2. For signed 8-bit values the leftmost column has weight −128, not +128.
  3. The remaining seven columns have weights 64, 32, 16, 8, 4, 2 and 1.
  4. The leading sign bit is 1, so its signed contribution is -128.
  5. The lower seven bits contribute 114.
  6. Add those contributions: -128 + 114 = -14.
  7. As an unsigned pattern, the same eight bits represent 242.
  8. The signed range for eight bits is −128 through +127.
  9. Bitwise inversion alone yields 00001101; inversion plus one wraps modulo 256.
  10. The eight-bit negated pattern is 00001110.
  11. Answer: signed(11110010) = -14.

Final answer: -14

Foundations · Problem 0244

Interpret 11110011 as an 8-bit two’s complement value.

Try it on paper first. The worked answer is hidden below.

Reveal detailed solution →
  1. Treat 11110011 as exactly eight bits.
  2. For signed 8-bit values the leftmost column has weight −128, not +128.
  3. The remaining seven columns have weights 64, 32, 16, 8, 4, 2 and 1.
  4. The leading sign bit is 1, so its signed contribution is -128.
  5. The lower seven bits contribute 115.
  6. Add those contributions: -128 + 115 = -13.
  7. As an unsigned pattern, the same eight bits represent 243.
  8. The signed range for eight bits is −128 through +127.
  9. Bitwise inversion alone yields 00001100; inversion plus one wraps modulo 256.
  10. The eight-bit negated pattern is 00001101.
  11. Answer: signed(11110011) = -13.

Final answer: -13

Foundations · Problem 0245

Interpret 11110100 as an 8-bit two’s complement value.

Try it on paper first. The worked answer is hidden below.

Reveal detailed solution →
  1. Treat 11110100 as exactly eight bits.
  2. For signed 8-bit values the leftmost column has weight −128, not +128.
  3. The remaining seven columns have weights 64, 32, 16, 8, 4, 2 and 1.
  4. The leading sign bit is 1, so its signed contribution is -128.
  5. The lower seven bits contribute 116.
  6. Add those contributions: -128 + 116 = -12.
  7. As an unsigned pattern, the same eight bits represent 244.
  8. The signed range for eight bits is −128 through +127.
  9. Bitwise inversion alone yields 00001011; inversion plus one wraps modulo 256.
  10. The eight-bit negated pattern is 00001100.
  11. Answer: signed(11110100) = -12.

Final answer: -12

Foundations · Problem 0246

Interpret 11110101 as an 8-bit two’s complement value.

Try it on paper first. The worked answer is hidden below.

Reveal detailed solution →
  1. Treat 11110101 as exactly eight bits.
  2. For signed 8-bit values the leftmost column has weight −128, not +128.
  3. The remaining seven columns have weights 64, 32, 16, 8, 4, 2 and 1.
  4. The leading sign bit is 1, so its signed contribution is -128.
  5. The lower seven bits contribute 117.
  6. Add those contributions: -128 + 117 = -11.
  7. As an unsigned pattern, the same eight bits represent 245.
  8. The signed range for eight bits is −128 through +127.
  9. Bitwise inversion alone yields 00001010; inversion plus one wraps modulo 256.
  10. The eight-bit negated pattern is 00001011.
  11. Answer: signed(11110101) = -11.

Final answer: -11

Foundations · Problem 0247

Interpret 11110110 as an 8-bit two’s complement value.

Try it on paper first. The worked answer is hidden below.

Reveal detailed solution →
  1. Treat 11110110 as exactly eight bits.
  2. For signed 8-bit values the leftmost column has weight −128, not +128.
  3. The remaining seven columns have weights 64, 32, 16, 8, 4, 2 and 1.
  4. The leading sign bit is 1, so its signed contribution is -128.
  5. The lower seven bits contribute 118.
  6. Add those contributions: -128 + 118 = -10.
  7. As an unsigned pattern, the same eight bits represent 246.
  8. The signed range for eight bits is −128 through +127.
  9. Bitwise inversion alone yields 00001001; inversion plus one wraps modulo 256.
  10. The eight-bit negated pattern is 00001010.
  11. Answer: signed(11110110) = -10.

Final answer: -10

Foundations · Problem 0248

Interpret 11110111 as an 8-bit two’s complement value.

Try it on paper first. The worked answer is hidden below.

Reveal detailed solution →
  1. Treat 11110111 as exactly eight bits.
  2. For signed 8-bit values the leftmost column has weight −128, not +128.
  3. The remaining seven columns have weights 64, 32, 16, 8, 4, 2 and 1.
  4. The leading sign bit is 1, so its signed contribution is -128.
  5. The lower seven bits contribute 119.
  6. Add those contributions: -128 + 119 = -9.
  7. As an unsigned pattern, the same eight bits represent 247.
  8. The signed range for eight bits is −128 through +127.
  9. Bitwise inversion alone yields 00001000; inversion plus one wraps modulo 256.
  10. The eight-bit negated pattern is 00001001.
  11. Answer: signed(11110111) = -9.

Final answer: -9

Foundations · Problem 0249

Interpret 11111000 as an 8-bit two’s complement value.

Try it on paper first. The worked answer is hidden below.

Reveal detailed solution →
  1. Treat 11111000 as exactly eight bits.
  2. For signed 8-bit values the leftmost column has weight −128, not +128.
  3. The remaining seven columns have weights 64, 32, 16, 8, 4, 2 and 1.
  4. The leading sign bit is 1, so its signed contribution is -128.
  5. The lower seven bits contribute 120.
  6. Add those contributions: -128 + 120 = -8.
  7. As an unsigned pattern, the same eight bits represent 248.
  8. The signed range for eight bits is −128 through +127.
  9. Bitwise inversion alone yields 00000111; inversion plus one wraps modulo 256.
  10. The eight-bit negated pattern is 00001000.
  11. Answer: signed(11111000) = -8.

Final answer: -8

Foundations · Problem 0250

Interpret 11111001 as an 8-bit two’s complement value.

Try it on paper first. The worked answer is hidden below.

Reveal detailed solution →
  1. Treat 11111001 as exactly eight bits.
  2. For signed 8-bit values the leftmost column has weight −128, not +128.
  3. The remaining seven columns have weights 64, 32, 16, 8, 4, 2 and 1.
  4. The leading sign bit is 1, so its signed contribution is -128.
  5. The lower seven bits contribute 121.
  6. Add those contributions: -128 + 121 = -7.
  7. As an unsigned pattern, the same eight bits represent 249.
  8. The signed range for eight bits is −128 through +127.
  9. Bitwise inversion alone yields 00000110; inversion plus one wraps modulo 256.
  10. The eight-bit negated pattern is 00000111.
  11. Answer: signed(11111001) = -7.

Final answer: -7

Foundations · Problem 0251

Interpret 11111010 as an 8-bit two’s complement value.

Try it on paper first. The worked answer is hidden below.

Reveal detailed solution →
  1. Treat 11111010 as exactly eight bits.
  2. For signed 8-bit values the leftmost column has weight −128, not +128.
  3. The remaining seven columns have weights 64, 32, 16, 8, 4, 2 and 1.
  4. The leading sign bit is 1, so its signed contribution is -128.
  5. The lower seven bits contribute 122.
  6. Add those contributions: -128 + 122 = -6.
  7. As an unsigned pattern, the same eight bits represent 250.
  8. The signed range for eight bits is −128 through +127.
  9. Bitwise inversion alone yields 00000101; inversion plus one wraps modulo 256.
  10. The eight-bit negated pattern is 00000110.
  11. Answer: signed(11111010) = -6.

Final answer: -6

Foundations · Problem 0252

Interpret 11111011 as an 8-bit two’s complement value.

Try it on paper first. The worked answer is hidden below.

Reveal detailed solution →
  1. Treat 11111011 as exactly eight bits.
  2. For signed 8-bit values the leftmost column has weight −128, not +128.
  3. The remaining seven columns have weights 64, 32, 16, 8, 4, 2 and 1.
  4. The leading sign bit is 1, so its signed contribution is -128.
  5. The lower seven bits contribute 123.
  6. Add those contributions: -128 + 123 = -5.
  7. As an unsigned pattern, the same eight bits represent 251.
  8. The signed range for eight bits is −128 through +127.
  9. Bitwise inversion alone yields 00000100; inversion plus one wraps modulo 256.
  10. The eight-bit negated pattern is 00000101.
  11. Answer: signed(11111011) = -5.

Final answer: -5

Foundations · Problem 0253

Interpret 11111100 as an 8-bit two’s complement value.

Try it on paper first. The worked answer is hidden below.

Reveal detailed solution →
  1. Treat 11111100 as exactly eight bits.
  2. For signed 8-bit values the leftmost column has weight −128, not +128.
  3. The remaining seven columns have weights 64, 32, 16, 8, 4, 2 and 1.
  4. The leading sign bit is 1, so its signed contribution is -128.
  5. The lower seven bits contribute 124.
  6. Add those contributions: -128 + 124 = -4.
  7. As an unsigned pattern, the same eight bits represent 252.
  8. The signed range for eight bits is −128 through +127.
  9. Bitwise inversion alone yields 00000011; inversion plus one wraps modulo 256.
  10. The eight-bit negated pattern is 00000100.
  11. Answer: signed(11111100) = -4.

Final answer: -4

Foundations · Problem 0254

Interpret 11111101 as an 8-bit two’s complement value.

Try it on paper first. The worked answer is hidden below.

Reveal detailed solution →
  1. Treat 11111101 as exactly eight bits.
  2. For signed 8-bit values the leftmost column has weight −128, not +128.
  3. The remaining seven columns have weights 64, 32, 16, 8, 4, 2 and 1.
  4. The leading sign bit is 1, so its signed contribution is -128.
  5. The lower seven bits contribute 125.
  6. Add those contributions: -128 + 125 = -3.
  7. As an unsigned pattern, the same eight bits represent 253.
  8. The signed range for eight bits is −128 through +127.
  9. Bitwise inversion alone yields 00000010; inversion plus one wraps modulo 256.
  10. The eight-bit negated pattern is 00000011.
  11. Answer: signed(11111101) = -3.

Final answer: -3

Foundations · Problem 0255

Interpret 11111110 as an 8-bit two’s complement value.

Try it on paper first. The worked answer is hidden below.

Reveal detailed solution →
  1. Treat 11111110 as exactly eight bits.
  2. For signed 8-bit values the leftmost column has weight −128, not +128.
  3. The remaining seven columns have weights 64, 32, 16, 8, 4, 2 and 1.
  4. The leading sign bit is 1, so its signed contribution is -128.
  5. The lower seven bits contribute 126.
  6. Add those contributions: -128 + 126 = -2.
  7. As an unsigned pattern, the same eight bits represent 254.
  8. The signed range for eight bits is −128 through +127.
  9. Bitwise inversion alone yields 00000001; inversion plus one wraps modulo 256.
  10. The eight-bit negated pattern is 00000010.
  11. Answer: signed(11111110) = -2.

Final answer: -2

Foundations · Problem 0256

Interpret 11111111 as an 8-bit two’s complement value.

Try it on paper first. The worked answer is hidden below.

Reveal detailed solution →
  1. Treat 11111111 as exactly eight bits.
  2. For signed 8-bit values the leftmost column has weight −128, not +128.
  3. The remaining seven columns have weights 64, 32, 16, 8, 4, 2 and 1.
  4. The leading sign bit is 1, so its signed contribution is -128.
  5. The lower seven bits contribute 127.
  6. Add those contributions: -128 + 127 = -1.
  7. As an unsigned pattern, the same eight bits represent 255.
  8. The signed range for eight bits is −128 through +127.
  9. Bitwise inversion alone yields 00000000; inversion plus one wraps modulo 256.
  10. The eight-bit negated pattern is 00000001.
  11. Answer: signed(11111111) = -1.

Final answer: -1