#### notes

The area of a square = side × side (where ‘side’ means ‘the length of a side’). Study the following table.

SIde of a square (in cm) |
Area of the square (in `"cm"^2`) |

1 | `1 xx 1 = 1 = 1^2` |

2 | `2 xx 2 = 4 = 2^2` |

3 | `3 xx 3 = 9 = 3^2` |

5 | `5 xx 5 = 25 = 5^2` |

8 | `8 xx 8 = 64 = 8^2` |

a | `a xx a = a^2` |

Since, 4 can be expressed as 2 × 2 = 22, 9 can be expressed as 3 × 3 = 32, all such numbers can be expressed as the product of the number with itself.

Such numbers like 1, 4, 9, 16, 25, ... are known as square numbers. In general, if a natural number m can be expressed as `n^2`, where n is also a natural number, then m is a square number.

The numbers 1, 4, 9, 16 ... are square numbers. These numbers are also called perfect squares.