1, fingering rules. The thumb represents the number 5, the fingers other than the thumb are called "group fingers", and each finger represents the number 1, so one hand adds up to the number 9.

2, fingering positioning. The left hand represents ten digits, the right hand represents single digits, and the fist clenched represents the number 0.

3. Finger method. For example, the number 2 1 means two fingers in the left hand and one finger in the right hand; The number 90 means that the left hand opens its five fingers and the right hand makes a fist.

4. The skill of addition. For example, 2 1+ 1 means that the left ten digits (2+ 1) plus a finger and the right ten digits (1+1) plus a finger can get the result 32.

5, the skills of subtraction. For example, 53- 12 means that the fingers of the left hand are reduced by one finger (5- 1) and the fingers of the right hand are reduced by two fingers (3-2), and the result is 4 1.

6. When the subtraction of ten digits is equal to 0 and you need to abdicate, see the formula of "retreat 1 addition and subtraction" below.

Advanced number sense has four stages:

1, advanced first-order sense

Count in order. That is, count down from 1 to100;

2, number sense advanced second order

Inverse number After the child has laid a solid ordinal foundation, he can start counting down. They can count down from 10 to 1 first, then increase the difficulty from 20 to 1, and then gradually increase to 100 to 1, which is very beneficial to the subtraction calculation.

3. Advanced third-order sense

The number of specific intervals. For example, there are two intervals, 1, 3, 5...2, 4, 6 ... Here, you can also start to explain the concepts of odd and even numbers to children.