With this trick, you will be able to
multiply any two numbers from 11 to 19 in your head quickly, without the use of
a calculator.

Step 1: Multiply the unit digit of both numbers and write down the ones; carry, if any. This gives the one’s digit of the answer.Step 2: Add the unit digit of the smaller number (preferable) to the whole number of larger number (or vice versa) and add carried digit. Write it down.

Take

**15 x 13**for an example.- Multiply 5 by 3 to get 15; write 5, carry 1.
- Add 3 to 15 to get 18; add 1 getting 19. Write 19.

Let’s
try another example:

**17 x 18 =?**

Step
1: 8 x 7 = 56; write 6, carry 5.

Step
2: 18 + 7 = 25; 25+5 = 30; write 30.

So,
17 x 18 = 306

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