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21 (number) facts for kids

Kids Encyclopedia Facts
This article is about the number 21. For the year, see 21.

Twenty-one is a special number that you see all around you! It comes right after twenty and just before twenty-two. It's an odd number, which means you can't divide it evenly by two.

Twenty-one can be divided perfectly by a few other numbers too. These are 1, 3, 7, and 21 itself.

The Number 21

The number 21 is important in many ways. For example, it's the name of a very popular card game. In this game, players try to get cards that add up to 21 without going over.

In Roman numerals, which were used by the ancient Romans, the number 21 is written as XXI. This is made up of two 'X's (which mean 10 each) and one 'I' (which means 1). So, X + X + I equals 10 + 10 + 1, which is 21!

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21 (number) Facts for Kids. Kiddle Encyclopedia.