The numbers to be filled in the title are as follows:

The specific calculation formula is:

1, transverse formula:

2+ 1 1-9=4

4- 1x0=4

2+7-5=4

2. Vertical formula:

2+4÷2=4

1 1- 1x7=4

9-0-5=4

Extended data:

Operation order of elementary arithmetic:

When calculating at the same level, calculate from left to right in turn;

Two-stage operation, first multiply and then divide, then add and subtract.

When there are brackets, count the inside of brackets first, and then count the outside of brackets;

When there are multiple brackets, count the brackets first, then the brackets inside, then the braces inside, and finally the brackets outside.

If there is a power, calculate the power first.

When performing mixed operations, the numbers in parentheses are calculated first, and the parentheses are from small to large. If there is a power, calculate the power first, and then from high to low.

References:

Elementary arithmetic Baidu encyclopedia