Off-form calculation, also known as recursive calculation (the name of recursive calculation is used in Shanghai Education Edition of Grade Three), needs to write down the calculation process completely, which is vertical calculation outside the form. Off-balance-sheet calculation calculates one formula at a time until the final result is calculated.

Some examples

1、30-( 19+2)。

2、(26+28)÷9。

3、3+2×8。

4、(3+5)×6。

5、36÷9×6。

6、 180÷9- 18。

7、(48+52)÷2 1。

8、 100-25×420+80×3。

9、7×(34+56)。

10、 105×2×5。

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, 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.