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Binary numbers
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Computers store everything as 1s and 0s. Learn how a row of bits can stand for a number.
Why binary?
A computer is made of billions of tiny switches called transistors. Each one is either off or on: 0 or 1.
A single 0 or 1 is a bit (binary digit).
We count in base 10 (denary). Computers count in base 2 (binary).
A single 0 or 1 is a bit (binary digit).
We count in base 10 (denary). Computers count in base 2 (binary).
Place values
Each column is worth double the one to its right.
Binary to denary
Write the bits under the place values.
Add up the place values that have a 1 under them.
00001010 = 8 + 2 = 10.
With 8 bits the biggest number is 11111111 = 255, and there are 256 different values (0 to 255).
Add up the place values that have a 1 under them.
00001010 = 8 + 2 = 10.
With 8 bits the biggest number is 11111111 = 255, and there are 256 different values (0 to 255).
Convert 01100001 to denary.
- Place values with a 1: 64, 32 and 1.
- 64 + 32 + 1 = 97
Answer: 97
Binary uses place values 128, 64, 32, 16, 8, 4, 2, 1. Add the values that have a 1. 8 bits can hold 0 to 255.
The interactive lesson includes the diagrams for this topic.
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