What is binary in simple words?

Binary is a way of writing numbers using only two digits, 0 and 1. Computers use it because their internal switches can only be off (0) or on (1).

Why do computers use only 0 and 1?

A computer is built from billions of tiny switches that have just two states: off or on. Representing off as 0 and on as 1 lets the computer store and calculate with these switches, so two digits are all it needs.

How do you read a binary number like 1010?

Give each switch its place value, doubling from the right: 8, 4, 2, 1. Add the values where the digit is 1. So 1010 is 8 + 0 + 2 + 0 = 10.

What is the difference between binary and the numbers we use every day?

Everyday numbers use ten digits (0–9) and place values that multiply by ten. Binary uses only two digits (0 and 1) and place values that double — 1, 2, 4, 8, and so on.

Is binary too hard for primary-school children?

No. Children who already understand counting and place value can grasp binary, because it follows the same rolling-over rule as decimal — a switch flips back to 0 and the next one turns on, just like 9 becomes 10.

How Binary Counts With 0s and 1s

Math Interactive lesson Free to play

Binary is a number system that writes every value using only two digits: 0 and 1. It is the way computers store and count, because the tiny switches inside a computer can only be in two states — OFF (0) or ON (1). Our everyday numbers use ten digits (0–9) and are called the decimal, or base-ten, system; binary is base-two.

In binary, the position of each digit decides its value. Reading from the right, the place values double at every step: 1, 2, 4, 8, 16, and so on. To read a binary number you take the value under each switch that is ON, ignore the OFF ones, and add the ON values together. For example, 1010 means 8 + 0 + 2 + 0 = 10.

Counting up works like normal numbers: when a switch is already 1 and must go higher, it flips back to 0 and the next switch turns on — the same way 9 rolls over to 10. Learners come away understanding place value, doubling, and how a code of just two symbols can represent any whole number.

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A secret code of 0s and 1s

🤖💡 How computers count: binary! Computers can't read all our numbers like 1, 2, 3 … 9. Inside, they only understand two things: 0 = OFF 1 = ON Think of tiny light switches. A computer is full of millions of them. By turning them off (0) and on (1), it can write any number. Let's learn the code together. Tap Next to begin! 👉
Only two digits: 0 and 1

Off or On — that's it Our normal numbers use ten digits (0–9). Binary uses only two: 0 and 1. Tap the bulbs to flip them off and on. There are no other choices — that's why it's called binary (bi means two)! 💡0OFF 💡0OFF 💡0OFF Tap any bulb to switch it on. 🖐️
Each spot has a value

Every switch has a value In binary, the spot a switch sits in tells you its worth. Reading from the right, the values double each step: 1, 2, 4, 8 … Tap each card to reveal its value 👇 4th spot 🤔= 8 3rd spot 🤔= 4 2nd spot 🤔= 2 1st spot 🤔= 1 Reveal all four to see the doubling pattern! See it? 1 → 2 → 4 → 8. Each one is double the one before. ✨
Turn switches into a number

Add up the ON switches To read a binary number: turn the ON (1) values into their numbers, then add them. OFF (0) switches add nothing. Tap the switches below and watch the total change! 08 04 02 01 Binary 0000 = 0 Example: turn on 4 and 1 to make 5 (4 + 1)!
Count up like a computer

Watch binary count: 0, 1, 2, 3 … When the last switch is already 1 and needs to go up, it flips back to 0 and the next one turns on — just like 9 → 10 in normal counting! 0 in binary +1 ➕ Reset ↺ Press +1 a few times and watch the 0s and 1s flip!
Crack the code!

Your turn to decode 🔍 Here is a binary number. Use the values under each switch to add up the ON ones, then pick the answer. 18 04 12 01 Binary 1010 = ? (hint: 8 + 2) 9 10 12 5 Pick the total of the ON switches.
You speak binary!

🏆🤖Brilliant — you can read binary! What you learned: 💡 Binary uses only two digits: 0 (off) and 1 (on). 🔢 Each spot has a value that doubles: 1, 2, 4, 8 … (from the right). ➕ To read a number, add up the values of the switches that are ON. 🔁 Counting up flips switches just like 9 → 10 in normal numbers. Example: 1010 = 8 + 2 = 10 Every photo, song and game on a computer is really just lots and lots of 0s and 1s. Now you know their secret! 🌟

Frequently asked questions

What is binary in simple words?: Binary is a way of writing numbers using only two digits, 0 and 1. Computers use it because their internal switches can only be off (0) or on (1).
Why do computers use only 0 and 1?: A computer is built from billions of tiny switches that have just two states: off or on. Representing off as 0 and on as 1 lets the computer store and calculate with these switches, so two digits are all it needs.
How do you read a binary number like 1010?: Give each switch its place value, doubling from the right: 8, 4, 2, 1. Add the values where the digit is 1. So 1010 is 8 + 0 + 2 + 0 = 10.
What is the difference between binary and the numbers we use every day?: Everyday numbers use ten digits (0–9) and place values that multiply by ten. Binary uses only two digits (0 and 1) and place values that double — 1, 2, 4, 8, and so on.
Is binary too hard for primary-school children?: No. Children who already understand counting and place value can grasp binary, because it follows the same rolling-over rule as decimal — a switch flips back to 0 and the next one turns on, just like 9 becomes 10.

How Binary Counts With 0s and 1s

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Frequently asked questions

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