Lesson

How Computers
Count

01 / 17

Computers only understand two things.

On and off. That's it!

02 / 17

Like a light switch.

It's either on... or it's off.

03 / 17

We write OFF as 0 and ON as 1.

These are called "bits" — the tiniest piece of information.

04 / 17

One bit can be 0 or 1.

That's only two different numbers!

05 / 17

What if we need bigger numbers?

We add more bits!

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Each bit has a special value.

The right bit is worth 1. The left bit is worth 2.

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Turn on the right bit to make 1.

Just the 1's place is on.

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Turn on the left bit to make 2.

Just the 2's place is on.

09 / 17

Turn on BOTH to make 3!

2 + 1 = 3. We add the values of the ON bits.

10 / 17

Let's add more bits!

Each new bit is worth DOUBLE the one before it.

11 / 17

8, 4, 2, 1.

Remember this pattern! Each doubles as you go left.

12 / 17

To make 5, turn on 4 and 1.

4 + 1 = 5. That's 0101 in binary!

13 / 17

To make 10, turn on 8 and 2.

8 + 2 = 10. That's 1010 in binary!

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Turn them ALL on to make 15.

8 + 4 + 2 + 1 = 15. The biggest number with 4 bits!

15 / 17

Your turn! Can you make 7?

Click the circles to turn them on or off.

16 / 17

Now try making 12.

Which bits add up to 12?

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Now play and explore!

Try making any number from 0 to 15.

0

Complete

You speak binary now.

Every number, letter, picture, and video on a computer is just a long string of 1s and 0s. You just learned the secret language of machines.

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