# Squares

The first ten square numbers are –

1, 4, 9,
16, 25, 36, 49, 64, 81,
100 ...

Each is the result of multiplying
a number by itself –

1 × 1, 2 × 2, 3 × 3, 4 × 4, 5 × 5 ...

– which can also be written –

1^{2}, 2^{2}, 3^{2},
4^{2}, 5^{2} ...

– where the small ^{2} 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*

Based on the book *Numbers: Facts, Figures & Fiction*.