Suppose that *f(n) = 25 * n ^{2} *.

n | f(n) |

2 | 100 |

3 | 225 |

4 | 400 |

5 | 625 |

6 | 900 |

The log-log graph makes it obvious that *f(n)* is *O(n ^{2})*.

The points that are plotted from the function lie on a straight
line that is parallel to a known *O(n ^{2})* line.