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