Add the formula table within 20, and recite it from left to right according to the same number.

Subtraction table of abdication within 20, according to the same minuend, from left to right.

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)