When calculating the addition and subtraction within 10 thousand vertically, the numbers on the same digit should be aligned.

When calculating the addition and subtraction of numbers within 10,000, it should be noted that the same digits should be aligned, starting with single digits, which digits add up to ten and one goes forward. Which number is not reduced enough, it should be reduced again.

Subtraction formula

1, minuend-subtrahend = difference

2. Difference+Minus = Minus

3, the minuend-difference = reduction

Subtraction correlation characteristic

1, inverse exchange rate: subtraction is inverse exchange. If a and b are any two numbers, then (a-b)=-(b-a).

2. Anti-association rule: subtraction is anti-association. When trying to redefine subtraction, then a-b-c=a-(b+c).