Ten-level method: a method used to calculate the abdication subtraction within 20, that is, divide the number to be subtracted into two numbers, subtract the first number from the minuend equal to 10, and then subtract the second number from 10 to get the final result.

The following figure can better illustrate the flat ten method:

For example, 15-8=7 can divide 8 into 5 and 3, so the algebraic expression can be divided into15-5 =10-3 = 7.

Extended data

Even ten method is also one of the four operations, and the addition and subtraction algorithm is as follows:

1, integer: aligned with single digits, starting from single digits, and advancing to higher digits when adding more than tens of digits; If the subtraction is not enough, subtract 1 from the high position. When this number is added to 10, it will decrease.

2 Decimal: decimal point alignment (that is, same digit alignment); Calculate according to the law of integer addition and subtraction; Align the decimal point with the horizontal line in the number and point the decimal point;

3. Add and subtract fractions and denominator fractions, with the denominator unchanged, and only add and subtract numerators; For the addition and subtraction of fractions with different denominators, the division operation is carried out first, and then the calculation is carried out according to the addition and subtraction algorithm of fractions with the same denominator; Quotes that do not result in the simplest score are divided into the simplest scores.