In the previous section, we expressed numbers as powers of 10. This is termed the base of the expression. However the base can be any number so that:

100 | = | 10 × 10 | = | 10^{2} |
Base 10: Power 2 |

16 | = | 2 × 2 × 2 × 2 | = | 2^{4} |
Base 2: Power 4 |

27 | = | 3 × 3 × 3 | = | 3^{3} |
Base 3: Power 3 |

625 | = | 5 × 5 × 5 × 5 | = | 5^{4} |
Base 5: Power 4 |

and so on …

In power notation (also called scientific notation) any number can be represented as a power of 10 so that:

325 is between 100 (10^{2}) and 1 000 (10^{3}) and is equal to 3.25 × 100 = 3.25 × 10^{2}

625 400 is between 10^{5} and 10^{6} and is equal to 6.254 × 10^{5}

There are two special cases of powers. Any number raised to the power of 1 is itself, and any number raised to the power 0 equals 1.