The first versions of ASCII used 7-bit codes, which meant they could attach a character to every binary number between 0000000 and 1111111, which is 0 to 128 in decimal.

Python makes a pretty nice interactive calculator. You can do the other way around, too, with the builtin function bin(x). (And there are also hex() and oct() builtins, if you also need to go back ...

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.

Binary code is used widely in computer programming, so it is important to learn what it means and how to use it. Denary The decimal number system, which we use everyday, is called denary .