Operation sequence of four operations:

1. If there is only addition and subtraction or only multiplication and division, it is calculated from left to right.

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, calculate the tertiary operation first, 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.

There are two main points in the calculation of column vertical pen: the same digit alignment, starting from the unit. If you don't carry, you can add ten digits first, but it is not recommended for carrying addition later. The format of exercise books is strictly in accordance with the following requirements:

1, the horizontal formula is written from the left end of the horizontal grid line in the math book.

2. The first addend in vertical form is written under the second addend in horizontal form, and the plus sign is aligned with the plus sign in horizontal form. The same numbers of addend, addend and sum must be aligned.

3. After calculating the vertical columns, don't miss the horizontal numbers.