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Number Systems

Data Representation · 4 question types

Exam Frequency Analysis

Past paper frequency (2018 to 2024)

This topic accounts for approximately 12% of your exam marks.

stable
High
Stable12%

Binary/hex conversion and binary arithmetic appear in every Paper 1. Consistently 8 to 15 marks.

There are two methods for each direction. Method 1 goes through binary as a stepping stone and is foolproof; method 2 uses arithmetic directly and is faster once you are confident.

Denary to hex, Method 1: via binary

  1. Convert the denary number to an 8-bit value.
  2. Split the binary value into two (groups of 4 bits).
  3. Convert each nibble to its denary value (0 to 15).
  4. Write each value as a hex digit using the A to F table for 10 to 15.

Denary to hex, Method 2: divide by 16

  1. Divide the number by 16. The whole part is the first hex digit; the remainder is the second hex digit.
  2. Convert any value 10 to 15 to its hex letter (A to F).

Hex to denary, Method 1: via binary

  1. Convert each hex digit to a 4-bit binary nibble.
  2. Join the two nibbles into an 8-bit binary number.
  3. Convert the binary number to denary using place values.

Hex to denary, Method 2: multiply by 16

  1. Multiply the first hex digit by 16.
  2. Add the second hex digit to the result.