The binary system, also known as base two, counts in chunks of two. As an example, let's count this collection of asterisks: Using the base 10 counting system, we'd express this number as five (5).

But for numbers 20 through 80, they used a binary system, with separate, one-word terms for 20, 40 and 80. For really large numbers, they used powers of 10 up to at least 10 million.

Unlike our everyday counting system that uses tens, binary uses just two numbers, 0 and 1. Learn more with BBC Bitesize. Suitable for KS3 students.

The number 3 also suggests a different way of counting. Our familiar base 10 decimal system uses the 10 digits from zero to 9. Binary, our digital lingua franca, represents numbers using only the two ...