Squares

Each is the result of multiplying a number by itself -
1 x 1, 2 x 2, 3 x 3, 4 x 4, 5 x 5 ...
- which can also be written -
1, 2, 3, 4, 5 ...
- where the small means 'squared'.

The square of 7 is 49, and working backwards, we say the square root of 49 is 7.

All square numbers end in either a 0, 1, 4, 5, 6 or a 9. So if someone were to ask you if 225,736,192 was a square number, you could say 'no' right away because it ends in a 2.

If you subtract a square number from the next square number you get the odd numbers 3, 5, 7, 9 ...

The first four square numbers

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