Here is a simple mathematical addition and subtraction. Only addition and subtraction operations need to be calculated from left to right. Calculate 3+5=8 first, then 8-2=6. The result is 6. Just enter 6 when you enter the verification code.

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Matters needing attention in comprehensive calculation formula (four operations):

1. If there is only addition and subtraction or only multiplication and division, it is calculated from left to right. For example, 2+ 1- 1=2, first calculate the number of 2+ 1, and then subtract 1 from the number of 2+ 1.

2. If primary operation and secondary operation exist at the same time, the secondary operation is calculated first.

3. If there are primary, secondary and tertiary operations (i.e. power, root and logarithm operations) at the same time, first calculate the tertiary operation, and then calculate the other two levels.

4. If there are brackets, count the numbers in brackets first (no matter what level, count first).

5. The third level should be counted in brackets, and then the second and first levels should be counted.

Baidu encyclopedia-four operations