Binary, hex and number conversion
OCR GCSE Computer Science revision on Binary, hex and number conversion. Aligned to the OCR GCSE Computer Science J277 specification. This bank has 108 practice questions on this topic.
Sample questions (3 of 108)
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Question 1
What is the decimal value of binary 1101?
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Answer: 13
Binary place values from right: 1, 2, 4, 8, 16, 32, 64, 128. So 1101 = 1×8 + 1×4 + 0×2 + 1×1 = 8 + 4 + 1 = 13. Build a quick table: 8 4 2 1, tick off the positions with 1s, sum them.
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Question 2
What is the decimal value of hexadecimal 2A?
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Answer: 42
Hex digits: 0-9 then A=10, B=11, C=12, D=13, E=14, F=15. Place values from right: 1, 16, 256. So 2A = 2×16 + 10×1 = 32 + 10 = 42. Hex is base-16; each digit represents 4 bits, so one hex digit = one nibble (half a byte).
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Question 3
Convert decimal 11 to binary (4-bit).
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Answer: 1011
From the place value table 8 4 2 1, you need 8 + 2 + 1 = 11. Put 1s in those positions: 1011. Check: 8 + 0 + 2 + 1 = 11 ✓. Any 4-bit binary number is in the range 0-15.
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105 more questions on Binary, hex and number conversion — plus mistakes tracking and spaced repetition across the whole Computer Science spec.