Digital data - CCEADenary to binary conversion

What is digital data, and how do computers understand it? How is digital data represented, stored, shared and manipulated?

Part ofDigital Technology (CCEA)Digital development concepts (programming)

Denary to binary conversion

Method one

One method used to convert a denary number into an 8-bit binary number is to mark down the bits needed to form the number in a placeholder grid.

Denary1286432168421
Binary
Denary
128
64
32
16
8
4
2
1
Binary

Worked example: Denary number 84

Mark down the highest powers of two required to form the number:

  • The highest power of 2 that fits into 84 is 64 (26), so mark a 1 below the 64.
  • Selecting 64 leaves a remainder of 20 (from the original 84). The highest power of 2 that fits into 20 is 16, so mark a 1 below the 16.
  • Selecting 16 still leaves 4 as a remainder. The highest power of 2 that fits into 4 is 4, so mark a 1 below the 4.
  • This leaves no remainders, so mark a 0 below the denary numbers you do not require.
Denary1286432168421
Binary01010100
Denary
128
64
32
16
8
4
2
1
Binary
0
1
0
1
0
1
0
0

This produces the 8-bit number 0101 0100, equivalent to 84 in denary (64 + 16 + 4).

Animation of method one for converting a denary number to binary

Method two

Another method to convert denary to binary is to divide the number by 2 and mark down the remainder (1 or 0).

Worked example: Denary number 83

  • \(83 \div 2 = 41\) (remainder 1)
  • \(41 \div 2 = 20\) (remainder 1)
  • \(20 \div 2 = 10\) (remainder 0)
  • \(10 \div 2 = 5\) (remainder 0)
  • \(5 \div 2 = 2\) (remainder 1)
  • \(2 \div 2 = 1\) (remainder 0)
  • \(1 \div 2 = 0\) (remainder 1)

Starting with the least significant bit (LSB), mark down the remainders

  • 1010011

As there are only seven digits in this binary number, you can make it into an 8-bit binary number by 'padding' the result with the required number of 0s on the left.

This produces the 8-bit binary number 0101 0011, equivalent to 83 in denary (64 + 16 + 2 + 1).

Animation of method two for converting a denary number to binary