Binary Numbers

Binary is a way of writing numbers using just two digits: 0 and 1. Computers use binary because they work with switches. Each switch can be on or off. On is 1 and off is 0. With just these two digits, computers can do amazing things.

How Binary Works

In our usual numbers, each spot is worth ten times more than the one before it. In binary, each spot is worth two times more. So 10 in binary means 2, not ten. And 100 in binary means 4. It takes more digits to write big numbers in binary.

A painting of Leibniz, who helped invent the idea of using ones and zeros.
A painting of Leibniz, who helped invent the idea of using ones and zeros. (Christoph Bernhard Francke / Wikimedia Commons)

Binary and Computers

Every picture, song, and game on a computer is made of binary. Computers turn letters and colors into long strings of 0s and 1s. The computer then reads these to show what you want. Without binary, computers could not work. That is why binary is so important today.

Fun Facts

  • The number 5 in binary is written as 101.
  • Each 0 or 1 in binary is called a 'bit'.
  • Eight bits together make one 'byte'.

Did You Know?

A math thinker named Gottfried Leibniz wrote about binary numbers over 300 years ago, long before computers existed.