Mathematics, Algebra and Function

Grade 5- 8

Students use codes to learn pre-algebra concepts.

Facts and Reminders

Simple Codes

This is a simple code because 43 + 32 = 75.

43 | |

+ 32 | A = 7 C = 5 |

AC |

Using Reverse Operations

In the problem below, to crack the code you must subtract 98 from 123. The answer is 25.

Problem | Step | Check | Solution | |

98 | 98 | |||

+ DF | 123 - 98 = 25 | + 25 | D = 2 | F = 5 |

123 | 123 |

In this next problem, to crack the code, you must divide 1,428 by 42. The answer is 34.

Problem | Step | Check | Solution | |

42 | 42 | |||

x AF | x 34 | |||

168 | 1428 ÷ 42 = 34 | 168 | A = 3 | F = 4 |

1260 | 1260 | |||

1428 | 1428 |

Using Number Sense

In the problem below, you can try two ways to crack the code. One way is to try each digit 1 through 9. Another way is knowing that 6 = 2 x 3 and trying 2 first.

Problem | Check | Solution |

31 | 31 | |

x AA | x 22 | |

6A | 62 | A = 2 |

6A0 | 620 | |

68A | 682 |

In the next problem, you know that the only number that added to itself and equals 2 is 1.

Problem | Check | Solution |

BBB | 111 | |

+ BBB | + 111 | B = 1 |

2 2 2 | 222 |

In the problem below, ask yourself the question, "Which number times itself equals 9?" The answer is 3.

Problem | Check | Solution |

FFF | 333 | |

x F | x 3 | F = 3 |

999 | 999 |

- Code Cracking activity sheet
- pencils