When using "truncation method" in addition and subtraction, add and subtract directly from the upper left bit (and pay attention to whether the next bit needs carry and dislocation) until you get the answer with required accuracy. When using truncation method in multiplication or division, in order to make the result as accurate as possible, we need to pay attention to the direction of truncation approximation:

First, to expand (or shrink) a multiplier, it is necessary to shrink (or expand) another multiplier;

Second, to expand (or reduce) the dividend, you need to expand (or reduce) the divisor. If you are seeking the sum or difference of two products (that is, a*b+/-c*d), you should pay attention to:

Third, expand (or shrink) one side of the plus sign, you need to shrink (or expand) the other side of the plus sign;

Fourth, to expand (or shrink) one side of the minus sign, you need to expand (or shrink) the other side of the minus sign.

Extended data 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 method: subtraction is anti-association. When trying to redefine subtraction, then

a-b-c=a-(b+c)