I have this project to do about crosses and I can't think of what the answer is for the following questions: What is the area rule of the crosses (the table below will help you)?

Cross Number | Area sq cm |

1 | 5 |

2 | 13 |

3 | 25 |

4 | 41 |

5 | 61 |

I also need to know what the formula is for it?