computation rule
Integer addition and subtraction
Align the numbers and add them from the lower order.
Decimal addition and subtraction
Align the decimal points, and then operate according to the law of integer addition and subtraction.
Fractional addition and subtraction
When the denominator is the same, add and subtract the numerator directly; When the denominator is different, divide first, then add and subtract.
Integer multiplication
The same number is aligned, counting from the last digit of multiplication, multiplying the multiplicand by each digit of multiplication to get the sum of the last digit of this number.
Multiplier alignment.
Integer division
Starting from the highest digit of the dividend, except to which digit of the dividend is written, the remainder is divided every time.
The following numbers must be less than the remainder.
Fractional multiplication
Use the product of molecular multiplication as the numerator and the product of denominator multiplication as the denominator.
decimal
The number A divided by the number B (except 0) is equal to the reciprocal of the number A multiplied by the number B.
Decimal multiplication
When multiplying a decimal by an integer, first calculate the product according to the law of integer multiplication, and then see how many decimal places the multiplicand has, starting from the right side of the product.
Count several people and point to the decimal point.
Decimal division
When the divisor is an integer, according to the law of integer division, the decimal point of quotient should be aligned with the decimal point of dividend;
When the divisor is decimal, first move the decimal point of the divisor to make it an integer, and then move the decimal point of the divisor to the right by a few.
Bits, the decimal point of the dividend is also shifted a few places to the right (if the number of digits is not enough, it is supplemented by "0") and then it is an integer according to the divisor.
The law of fractional division is used for calculation.