The so-called abacus mental arithmetic is abacus mental arithmetic. Abacus calculation is a calculation method that uses abacus as a tool to perform operations such as addition, subtraction, multiplication, division and square root. There are certain rules and formulas in the skill of transporting beads. When the user can skillfully operate the abacus, he can not only get the correct answer quickly, but also describe the disk type, grade and floating change of the abacus in his mind through the growth of brain cells. This vivid abacus image is called "virtual disk". It completes abacus calculation in the brain through the process of perception, image and memory, which is what we call abacus mental calculation.

The speed of mental arithmetic is amazing. Often, as long as you hear the number of questions or see the calculation questions yourself, the calculator can blurt out the answers or write them out immediately. So abacus mental arithmetic technology.

addition formula

Add (at most) to the last five.

(Next five to several) Add ten.

(Go to several places and enter several places) Add it to five places and enter ten places.

(Up and down several times, five into one)

Subtraction formula

Subtract five (times)

(Up and down, to five) Subtract directly from ten.

(Several times) Borrow (return) ten to make up five subtraction.

(Go back several times, come back five times)

The division of nine belongs to the formula:

One time (divided by 1): one time, two times, three times, four times, five times, six times, seven times, eight times and nine times.

Two returns (divided by two): every two into one, every four into two, every six into three, every eight into four, 2 1 plus five.

Three returns (divided by three): three into one, six into two, nine into three, three into one, three into two.

Four returns (divided by four): every four enters one, every eight enters two, four two adds five, four twelve is more than two, and four thirty-seven is more than two.

Five cycles (divided by five): every five cycles into one, 5 1 cycle is two, 52 cycles is four, 53 cycles is six, and 54 cycles is eight.

Six returns (divided by six): one every six, two every twelve, six three plus five, six one plus four, six two three left two, six four left four, six five eight left two.

Seven returns (divided by seven): every seven returns to one, every fourteen to two, every seven to three, every seven to six, every seven to four, every seven to five, every seven to five and every seven to four.

Eight returns (divided by eight): every eight enters one, 84 adds five, 8 1 adds two, 82 adds four, 83 adds six, 856 is greater than two, 867 is greater than four, and 878 is greater than six.

Nine returns (divided by nine): every nine returns to one, nine returns to one, ninety-two returns to two, ninety-three returns to three, ninety-four returns to four, ninety-five returns to five, ninety-six returns to six, ninety-seven returns to seven and ninety-eight returns to eight.

Division and quotient extraction formula

Only refund, only refund, two, three,

Did not return 4, did not return 5, did not return 6,

No return 7, no return 8, no return 9,

Nine formulas of division quotient

See no score 9 1, see no score 92, see no score 93,

See four division is 94, see five division is 95, and see six division is 96.

Don't divide 97 by seven, 98 by eight, and 99 by nine.