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Teens

# Teen numbers: monkeys

Sal breaks the number 18 into 10 and 8. Created by Sal Khan.

## Want to join the conversation?

• what is 567490005 + 2330009987=
• It Is 2897499992
(1 vote)
• So knowing place value makes adding subjects easier?
• Nope it makes it million times harder than ever before!
• you need 8 monkeys to make 18
• You are on the right track. You need 8 monkeys and an additional 10 monkeys to make 18 monkeys. 8+10=18
• How do you count in binary, and what is 18 in binary?
(1 vote)
• I think @Jerry Nilsson did a great job explaining how to write in binary, but he never went over what binary is, and why we do it the way we do it.

The binary number system is a base 2 number system. That means that each place value is two times more than the last place value. For example, we may have ones, tens and hundreds, and binary may have, ones, twos, fours, eights, and so on.
Being a base 2 number system also means it consists of two characters, or symbols. These symbols are ones and* zeros*. This means we add another place value every time one of the numbers becomes greater than the largest digit, which is one. (In base ten, what we write in, the largest digit is 9)
So instead of counting like `0, 1, 2, 3, 4, 5, 6, etc.`, binary counts like this; `0, 1, 10, 11, 100, 101, 111, 1000, 1001, 1011, 1111, etc.` So instead of adding another digit after 9, `(6, 7, 8, 9, 10)`, we add another digit after the number 1. `(0, 1, 10)`.

• Would the same idea work for hundreds?
• Yes the same idea should work for hundreds. However if you where to work with monkeys you would have quite a few monkeys on your hand.
• So, let's talk about The Loud House: There are 10 sisters, 1 brother, and 2 parents. How many people are there in total?
• There is 13 people.
• is zero the last number in the numbers?
• There are an infinite amount of numbers! Even ones below 0. They are called negative numbers. Before 0 is negative 1, and before negative 1 is negative two. Here is a number line that might help.
-5 -4 -3 -2 -1 0 1 2 3 4 5
|---|---|---|---|---|---|---|---|---|---|---|---|
I started at -5, but there are many more numbers before that. Think of it in terms of cookies. Maybe there were 2 cookies. One for you and one for your friend. But, your friend took your cookie. So now, they owe you a cookie. This is the same as saying the have -1 cookies. They have two cookies, they owe you one. Now they have one cookie. That is the same as 2 plus -1. Or, just 2 minus 1. Crazy, right?