There are quick ways to multiply two numbers, and these patterns of multiplication are easy to remember. Here are some patterns involved in multiplying numbers by 2, 5, 6, 9, 12, and 20.

To multiply |
How to do it |
Example to Multiply |
---|---|---|

2 |
add the number to itself | 2 x 11 = 11 + 11 = 22 |

5 |
the last digit of the number follows the pattern 5, 0, 5, 0 | 5 x 1 = 55 x 2 = 1 05 x 3 = 1 55 x 4 = 2 0 |

6 |
multiplying 6 by any even number gives an answer that ends in the same last digit as the even number | 6 x 12 = 726 x 8 = 48 |

9 |
multiply the number by 10, then subtract the number | 9 x 7 = 10 x 7 – 7 = 63 |

12 |
multiply the original number first by 10, then multiply the original number by 2, and then add the two answers | 12 x 12 = ? 12 x 10 = 120 12 x 2 = 24 120 + 24 = 144 |

20 |
multiply the number by 10 then multiply the answer by 2 | 14 x 20 = 14 x 10 = 140 140 x 2 = 280 |