Back to Topic 1.2 — Data representation and logic
1.2.1Computer Science SL5 flashcards

Binary and hex

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Card 1 of 51.2.1
1.2.1
Question

How do you convert a binary number to decimal?

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All 5 Flashcards — Binary and hex

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Card 1process

Question

How do you convert a binary number to decimal?

Answer

Write the column values above it — 128 64 32 16 8 4 2 1 — and add the columns that have a 1 under them. 10110101 = 128 + 32 + 16 + 4 + 1 = 181.

Card 2process

Question

How do you convert a decimal number to binary?

Answer

Take the biggest column value that fits, subtract it, and repeat with what is left. 181: 128 fits (53 left), 32 fits (21), 16 fits (5), 4 fits (1), 1 fits (0) — so 10110101. Add the columns back to check.

Card 3concept

Question

Why does one hex digit equal exactly four bits?

Answer

Four bits can hold the values 0 to 15, which is exactly the range of a single hex digit (0 to F). So any four bits swap cleanly for one character.

Card 4process

Question

How do you convert binary to hexadecimal?

Answer

Group the bits in fours starting from the right, padding the leftmost group with zeros, then turn each group into its digit. 101101 is 0010 1101, which is 2D.

Card 5definition

Question

What are the hex digits above 9?

Answer

A = 10, B = 11, C = 12, D = 13, E = 14, F = 15. To convert two hex digits to decimal, multiply the left by 16 and add the right: B5 = 11 × 16 + 5 = 181.

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