Why do computers use binary numbers?

Binary numbers to most people are like car engines: we know they exist and that they’re important, but we don’t know how or why they work. But besides that, we just accept that a bunch of 1s and 0s run our computers and we’re fine with that. But in this article, I am going to explain why we use a binary system (instead of the decimal system we are used to) and how to convert binary numbers to decimal numbers.


Decimal numbers use a base 10 system. That means that each time you move over one space left on a decimal number, that place value is worth 10 times more than the previous. And, starting from the rightmost spot on a number, or the 0th spot, each space as you move to the left can be labeled with consecutive numbers form 0. The value at each placeholder is 10 raised to the number of the placeholder.

To add of decimal numbers, we take the number at a specific placeholder, and multiply it times 10 to the value of the placeholder. And then we add up the values at each spot.

With binary numbers, we do the same thing, except the base is 2 instead of 10, and the options for the values at each placeholder is just 0 and 1.

Why do we use binary numbers?

We are all taught decimal numbers in school. They are the standard for numbers we use every day. So why do computers to binary? The answer is pretty simple. Most of circuitry in computers act as switches that control electrical signals, and the only required states for the switches are “on” and “off.” This requirement means they only need 2 numbers to represent each state, 0 and 1. If we used a decimal system for the switches, that would mean there would be 10 possible states to a switch. That is completely unnecessary, and I’ll explain why.

How many possible answers are there to the question, “Are you wearing sunglasses?” Basically, just 2. Yes or no. Same with the question, “Is the car on?” A car can be on or off, there is really no in between. With these kinds of questions, there are just two different states possible. The car or sunglasses are both off, or the car and the sunglasses could be on. So if you were to write a survey with these questions, which of the following would make more sense?

Survey 1

Survey 2

Obviously, Survey 1 would make a lot more sense, because these questions can be answered accurately with just 2 options. 10 is unnecessary. This same idea applies to why computers use binary numbers instead of decimal. Overall, binary numbers are more efficient and take up less space because each switch in a computer only needs 2 options instead of 10.