Four algorithms: 1+ 1 = 2, 1- 1 = 0, 1 ⅹ 1 = 1 ÷.
1, addition, subtraction, multiplication and division are called four operations. There are brackets in the formula. Please count the brackets first. In the formula without brackets, if there are only addition and subtraction operations or only multiplication and division operations, they should be calculated from left to right. There are multiplication and division and addition and subtraction, and multiplication and division must be calculated first.
2, about the algorithm of zero:
Add 0 to a number and you get the number.
Subtract 0 from a number and you get the number.
The minuend is equal to the minuend, and the difference is 0.
Multiply a number by 0 or multiply a number by 0 to get 0.
Divide 0 by a number that is not 0 to get 0. (Note: 0 is not divisible)
Formula:
① Add:
Additive commutative law: A+B = B+A;
Additive associative law: a+b+c = a+(b+c) = (a+b)+c;
② subtraction:
A-B =-(B-A)
a-b-c=a-(b+c)
There is a formula for subtraction: add brackets and change signs.
③ Multiplication:
Multiplicative commutative law: a x b=b x a
Law of multiplicative association: a x b x c=a x (b x c)
Law of multiplication and distribution: a x (b c) = a x b a x c
④ Division:
If a number is divided by (or multiplied by) a number and then multiplied by (or divided by) the same number, the number remains the same.
A number divided by the product of several numbers can be divided by the factors in the product in turn.
The quotient of a number divided by two numbers is equal to the number divided by the divisor in the quotient and then multiplied by the divisor in the quotient.
The product of several numbers is divided by a number, so that any factor in the product can be divided by this number and then multiplied by other factors.
When the sum of several numbers is divided by a number, you can divide each addend by this number first, and then add each quotient.
The difference between two numbers is divided by a number, and the quotient obtained by dividing the minuend by this number can be subtracted from the quotient obtained by dividing the minuend by this number.