How Do Computers Count to 1024 with Just On/Off Switches?

Imagine your house has a long row of light switches. Each switch can only be in one of two states: up for on and down for off. If you have just three switches, you can make different patterns to show numbers.

We humans use ten fingers, so we count using tens (0 through 9). Computers are like kids who only have two fingers, so they count in twos. They start at zero (off), then one (on).

When you turn on the next switch to the right, it represents double the value of the first one. It is like a row of dominoes where each one stands for a bigger number than the one before it.

With enough switches lined up, even small computers can count very high. A group of eight switches can hold a special code for every letter on your keyboard or every color in a photo. This is how your screen knows to draw a red circle instead of a blue square.