The simplest mental arithmetic method

The simplest mental arithmetic method is as follows:

1, no carry addition formula:

(1) Two digits plus one digit: write ten digits first, and then write the sum of the digits.

(2) Two digits plus two digits: write the sum of ten digits first, and then write the sum of one digit.

(3) Multi-digit plus multi-digit: write the sum of the numbers in the same position in turn from the high position.

2. Carry addition formula. The key of carry addition is to push 1 to a higher number. Since it's a definite thing, can you push 1? After observation, you can start counting from the high position.

3. Two digits plus one digit: write the sum of ten digits plus 1 first, and then write the single digits of the sum of single digits.

4. Two digits plus two digits: first, write down two digits to make a ten-digit number after integer ten, and then write down the remainder after dividing one digit by one.