Examples of multiplication in Shi Feng Harvest's accelerated algorithm

Like traditional multiplication, the quick math method deals with each digit of the multiplier bit by bit. The digit that is being dealt with in the multiplied number is called the "principal digit", and the digits from the first to the last digit on the right side of the principal digit are called the "posterior digits". After the first digit is multiplied, only the first digit of the product is taken, which is called the "first digit", while the second digit of the first digit is multiplied by the second digit of the multiplier and the number to be rounded off is called the "second digit".

Multiplication example

The first digit of the multiplied number is filled with zero, and the equation is:

0847536×2=1695072

The multiplier of 2 is "2 out of 5, 1 in"

0×2 this one is 0, and the second digit is 8, and then it goes into the second digit 1, which results in 1

8×2 this one is 6, and the second digit is 4, which does not go into the second digit, and then it results in 6

4×2 this 8, back 7, full 5 to 1,

8 ten 1 to 9

7×2 this 4, back 5, full 5 to 1,

4 ten 1 to 5

5×2 this 0, back 3, no entry, 0

3×2 this 6, back 6, full 5 to 1,

6 ten 1 to 7

6×2 this 2, no backspace, get 2

Here we only take the simplest example for readers to refer to, as for multiplying 3, 4 ...... to multiplying 9 also have a certain law of progression, limited to space, I can not list them here.

The "Shifeng Harvest" algorithm, which is based on these rounding rules, has been gradually developed, and as long as it is used skillfully, all four multi-digit arithmetic operations can be achieved quickly and accurately.