HP2-B101 · Question #32
What is the correct binary number for 255?
The correct answer is D. 11111111. D (11111111) is correct because 255 equals 2⁸ − 1, meaning every bit in an 8-bit number is set to 1: 128 + 64 + 32 + 16 + 8 + 4 + 2 + 1 = 255. A (00001111) represents only 15 - the lower four bits sum to 8+4+2+1. B (10101010) is an alternating pattern that totals 170, not 255…
Question
What is the correct binary number for 255?
Options
- A00001111
- B10101010
- C0111101
- D11111111
How the community answered
(21 responses)- A5% (1)
- D95% (20)
Explanation
D (11111111) is correct because 255 equals 2⁸ − 1, meaning every bit in an 8-bit number is set to 1: 128 + 64 + 32 + 16 + 8 + 4 + 2 + 1 = 255. A (00001111) represents only 15 - the lower four bits sum to 8+4+2+1. B (10101010) is an alternating pattern that totals 170, not 255. C (0111101) is only 7 digits (making it 61), and a proper 8-bit representation requires all 8 positions.
Memory tip: 255 is the largest value an 8-bit byte can hold - think "all bits maxed out," so all eight 1s. If you ever see 11111111, that's your maximum byte value, always 255.
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