Simple method calculation, referred to as simple operation, uses the characteristics between special numbers and the operation rules or properties to calculate skillfully.

The law of multiplication and distribution is: the sum of two numbers is multiplied by a number, and then multiplied by this number respectively, and the product is unchanged, that is, (a+b) × c = a× c+b× c, and vice versa: a× c+b× c = (a+b )× c.

Calculation method:

1, using the algorithm. The calculation can be simplified by using the commutative law and associative law of addition and the commutative law, associative law and distributive law of multiplication.

2. Decomposition factor. Some special numbers can be multiplied to get integers, such as 25 and 4, 125 and 8, etc. When we encounter these numbers, we can try to turn them into numbers that can get integers.

3. Digital distortion. Some numbers in the formula can't be transformed by simple methods, but we can transform some numbers by simple methods, and then we can transform them.

4. Arithmetic series. Some formulas have the same difference between adjacent numbers, so arithmetic progression formula can be used.

5. Set the numbering method. In some formulas, some numbers are the same, but the formulas are very long. At this time, we can set the formula composed of the same numbers as a letter, then replace the corresponding letter in the formula with a letter, and then calculate it, which is much simpler.

6. Rounding method. Some decimals are not much different from integers, and they are regular. We can make them into integers.

7. Split method. Split method is to split a number into several numbers for the convenience of calculation. This requires mastering some "good friends", such as 2 and 5, 4 and 5, 2 and 2.5, 4 and 2.5, 8 and 1.25. Be careful not to change the size of the number when splitting.