IGCSE Computer Science – Binary ↔ Decimal Conversion Worksheet
Part A – Quick Recap
1. Binary (Base-2): Uses only digits 0 and 1. Each place value represents a power of 2.
Example:
1011₂ = (1×2³) + (0×2²) + (1×2¹) + (1×2⁰) = 8 + 0 + 2 + 1 = 11₁₀
2. Decimal to Binary Conversion:
Divide the decimal number by 2 repeatedly, write down remainders, and read from bottom
to top.
Example:
13₁₀ → 1101₂
Part B – Practice: Binary → Decimal
1. 1001₂ = ______
2. 1110₂ = ______
3. 10101₂ = ______
4. 110011₂ = ______
5. 1001111₂ = ______
Part C – Practice: Decimal → Binary
1. 6₁₀ = ______
2. 12₁₀ = ______
3. 25₁₀ = ______
4. 45₁₀ = ______
5. 100₁₀ = ______
Part D – Mixed Challenge
1. Write the binary equivalent of the decimal number 255.
2. Convert 11111111₂ into decimal.
3. Convert 10101010₂ into decimal.
4. Convert decimal 73 into binary.
5. A number in binary is 100000₂. What is it in decimal?
Part E – Word Problems
1. A computer stores a pixel brightness value as 110010₂. What is the decimal value?
2. A student scored 37 marks in decimal. Write the score in binary.
3. The binary number 101110₂ represents the number of files in a folder. How many files
are there in decimal?
✨Extension (Optional Challenge)
1. Convert 101010101₂ to decimal.
2. Convert 511₁₀ into binary.