Abacus calculation is a digital calculation method with abacus as a tool. Carve the board into three parts, the upper and lower parts are used to block the beads and the middle part is used to locate them. Everyone has five beads. The upper bead and the lower four beads are distinguished by color. There are five beads on the top and four on the bottom, one for each bead.

First, the basic knowledge

1. Hold the pen: When calculating the abacus, keep the pen in your hand. When holding a pen, the upper end of the pen is sandwiched between the thumb and index finger of the right hand, and the lower end is sandwiched between the middle finger and ring finger of the right hand. At the same time, the palms of middle finger, ring finger and little finger naturally bend.

2. Liquidation: put the thumb and forefinger of the right hand together, move quickly from right to left along the beam, bounce the abacus back to its original position, leave the beam and lean against the frame.

3. Single file: The sixth file from the right is designated as a single file.

4. Basic fingering:

Fingering with the right hand: use your thumb and forefinger to pluck the beads, with your thumb pointing to the beam to lower the beads, and your forefinger pointing to the beam to upper the beads, lower the beam and lower the beam.

Fingering with left hand: use the index finger and middle finger to dial the beads, the other three fingers lightly hold the upper and lower frames of the abacus, and the index finger is responsible for placing the beads against the beam; The middle finger is responsible for the separation and leaning between the upper bead and the beam, and the left hand is mainly used to assist in handling.

Second, the basic concepts

1, complement: If the sum of two numbers is 5, the two numbers are said to be complementary. 1 complement 4,2 complement 3,3 complement 2,4 complement 1.

2. Complement: If the sum of two numbers is 10, it is said that the two numbers are complementary. The complement of 1 is 9, that of 2 is 8, that of 3 is 7, that of 4 is 6, that of 5 is 5, that of 6 is 4, that of 7 is 3, that of 8 is 2 and that of 9 is 1.

Fixed number plus 1: refers to continuously adding 1 to a fixed number, such as adding 1 to 100, which means continuously adding 1 until the answer is 100.

Numbers 2, 3, 4, 5, 6, 7, 8 and 9 are added, and the same number is added 1.

Third, the basic addition and subtraction

1, direct addition and direct subtraction:

Direct addition: the formula is "Look at the outer beads, add enough directly" Example 2+6.

Direct reduction: the formula is "reducing inner beads is enough to reduce direct reduction" Example 8-7

2. Add and subtract 5 categories:

Add up to 5: The formula is "If the direct addition is not enough, subtract 5". Example 4+2(2 subtracts 5 and supplements 3)

Round up and subtract from 5: the formula is "If direct subtraction is not enough, add 5" Example 8-4 (the sum of adding 5 and 4 is 1)

3. Add and subtract categories above10:

If it exceeds 10, it will be added: the formula is "This file exceeds 10, plus 10 minus complement" Example 7+8 (10 plus 1, one minus 8' s complement 2).

Subtract from 10: The formula is "This file is not enough, subtract 10 and add its complement" 10-6 (ten digits subtract 1, and the complement of 6 adds one digit).

4. Above 10, there are five categories:

If it exceeds 10, add 5: If it exceeds 10, add the formula, and subtract the formula, for example, 5+8 (if you add 1 to ten digits and subtract the complement of eight from one digit, "add 3 to 5").

10 minus 5: 10 minus the formula, and 5 plus the formula, for example, 1 3-7 (/kloc-0 minus10 digits, and "5 minus 2" when the complement 3 of 7 is added to single digits).