Mixed method of mathematical addition and subtraction

The mixing method of mathematical addition and subtraction is as follows:

Decimal number method: several numbers are added together. If the single digits of two addends add up to 10, the two numbers can be added first, and the ten digits within 10 can be added to 1.

Addition and subtraction in the unit of close to 10 (in the unit of 9): You can calculate this addend (or subtraction) as 10 first, and then add 1 (or subtract 1) to get the final result.

The calculation method of adding series within 100;

Oral calculation method: first add up the whole ten, then add up the digits, and finally add up the sum obtained by adding these two.

Written calculation method: first add the first two numbers, and then add the third number to sum up. Or directly add three numbers vertically, align the same numbers, start with one number, and add ten numbers to each number to advance several numbers.

100, the calculation method of continuous reduction of numbers;

From left to right, subtract the first two numbers, and then subtract the third number from the result.

Or first calculate the sum of the last two numbers 1, and then subtract this sum from the first number.

100 internal number addition and subtraction mixed operation method;

If there is only addition and subtraction in an equation, it should be calculated from left to right.

Addition, subtraction and mixed operation of addition and subtraction (Mandarin);

Without continuous addition,

Let's count the steps first.

There are continuous subtraction operations,

Go from left to right.

Addition, subtraction, mixing and continuous reduction,

Look from left to right in turn.