Multiply two consecutive numbers
Introduction
This is a simple approach to multiply two consecutive numbers in your mind. This approach will be useful while learning certain tricks that we'll be covering in our blogpost series.
What you need to know before you start...
You need to master Multiplication Tables (1 to 20) and Squares (1 to 30). Memorizing these essential concepts is crucial for any mathematics student. Our specially crafted worksheets on Multiplication and Squares will help you solidify this knowledge. Not only will it benefit this blog post, but it will also prove invaluable for numerous other topics covered on our blog.
Use the Times Tables Reference to learn and memorize.
The method is
To multiply any two consecutive numbers n and n + 1
(n)2 + n
or
(n + 1)2 - (n + 1)
| 11 ✕ 12 | 112 + 11 = 121 + 11 =or122 - 12 = 144 - 12 = | 132 |
| 12 ✕ 13 | 122 + 12 = 144 + 12 =or132 - 13 = 169 - 13 = | 156 |
| 13 ✕ 14 | 132 + 13 = 169 + 13 =or142 - 14 = 196 - 14 = | 182 |
| 14 ✕ 15 | 142 + 14 = 196 + 14 =or152 - 15 = 225 - 15 = | 210 |
| 15 ✕ 16 | 152 + 15 = 225 + 15 =or162 - 16 = 256 - 16 = | 240 |
| 16 ✕ 17 | 162 + 16 = 256 + 16 =or172 - 17 = 289 - 17 = | 272 |
| 17 ✕ 18 | 172 + 17 = 289 + 17 =or182 - 18 = 324 - 18 = | 306 |
| 18 ✕ 19 | 182 + 18 = 324 + 18 =or192 - 19 = 361 - 19 = | 342 |
| 19 ✕ 20 | 192 + 19 = 361 + 19 =or202 - 20 = 400 - 20 = | 380 |
| 20 ✕ 21 | 202 + 20 = 400 + 20 =or212 - 21 = 441 - 21 = | 420 |
| 21 ✕ 22 | 212 + 21 = 441 + 21 =or222 - 22 = 484 - 22 = | 462 |
| 22 ✕ 23 | 222 + 22 = 484 + 22 =or232 - 23 = 529 - 23 = | 506 |
| 23 ✕ 24 | 232 + 23 = 529 + 23 =or242 - 24 = 576 - 24 = | 552 |
| 24 ✕ 25 | 242 + 24 = 576 + 24 =or252 - 25 = 625 - 25 = | 600 |
| 25 ✕ 26 | 252 + 25 = 625 + 25 =or262 - 26 = 676 - 26 = | 650 |
| 26 ✕ 27 | 262 + 26 = 676 + 26 =or272 - 27 = 729 - 27 = | 702 |
| 27 ✕ 28 | 272 + 27 = 729 + 27 =or282 - 28 = 784 - 28 = | 756 |
| 28 ✕ 29 | 282 + 28 = 784 + 28 =or292 - 29 = 841 - 29 = | 812 |
| 29 ✕ 30 | 292 + 29 = 841 + 29 =or302 - 30 = 900 - 30 = | 870 |
| 30 ✕ 31 | 302 + 30 = 900 + 30 =or312 - 31 = 961 - 31 = | 930 |
Our worksheets
Once you've learnt this trick, please do visit Practice drill on squares worksheet page and put your learnings into practice.