Is the multiplication of 1 to 19 (→ 19 × 19? ),

But do you know how Indians remember the numbers 1 1 to 19?

It was after reading the following book that I suddenly realized.

On June 10, 2007, Jinyoushe released the first issue of Computing Training in India.

Various fast calculation methods of addition, subtraction, multiplication and division are introduced.

But here I only introduce India's 99 multiplication, because it's amazing! !

The following figures and explanations are examples that refer to page 44 of the book.

Please try to recite the following answers:

13 X 12 =？

(multiplicand) (multiplier)

That's what Indians do.

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Step one:

First, add (13) to the number of units of the multiplier (2).

13 + 2 = 15

Step two:

Then multiply the answer of the first step by 10 (→ is followed by a 0).

Step 3:

Multiply the single digits of the multiplicand (3) by the single digits of the multiplier (2)

2 x 3 = 6

( 13+2)x 10+6 = 156

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So you can quickly calculate11x1to19 by heart.

This is really amazing!

Let's try to calculate:

14 × 13:

( 1) 14 + 3 = 17

(2) 17 × 10 = 170

(3) 4 × 3 = 12

(4) 170 + 12 = 182

16 × 17:

( 1) 16 + 7 = 23

(2) 23 × 10 = 230

(3) 6 × 7 = 42

(4) 230 + 42 = 272