1 6x7 5x1 25 How to calculate easily

The calculation process is as follows:

Multiplication Properties:Multiply the product of several numbers by a number, so that any factor in the product can be multiplied by this number, and then multiplied by other numbers. For example:

Multiplying the difference between two numbers by one number allows the subtracted number and the subtracted number to be multiplied by this number, and then the resulting product is subtracted. For example: (137-125) 8=137 8-125 8=96.

Solution: Adopt the splitting method and the associative law, and the original formula ==

=15x1=15

Analysis: Through observation, first split into 2 multiplied by, and then use the multiplicative associative law to multiply 2 and multiply, and multiply and multiply, and the resulting product will be multiplied to get the final result. (Note the use of parentheses).

2 will be split into 2

2 Apply the law of associativity).

The concept of the associative law of multiplication is: multiply the first two numbers, or multiply the last two numbers, and the product does not change. Cavity fiber.

Letter formula: a b c = a (b c).

Interpretation: Simple calculation is a special kind of calculation, which uses the law of operation and the basic properties of the number of slow holes, so as to make the calculation simple, so that a very complex formula becomes easy to calculate the number.

Law: Multiplicative distributive law.

The associative law of multiplication.

The commutative law of multiplication.

The commutative law of addition.

Associative law of addition.

Note: When performing simple operations, you should pay attention to the relationship between the operation symbols (multiplication, division, addition and subtraction) and the large, medium and minor parentheses. Do not skip the arithmetic to avoid arithmetic errors. Disturbance.

× .Split

=(蚂en2 .Take the Zheng Que method of shouting early exchange and union law

5x（4-1）

Law. Multiplicative distributive property.

The most common method used in simple calculations is the multiplicative distributive property. The multiplicative distributive property refers to ax(b+c) = axb+axc, where a, b, c are arbitrary real numbers. On the contrary, axb+axc=ax(b+c) is called the inverse of the multiplicative distributive property (also called extracting the common divisor), especially when a and b are complements to each other, this method is more useful.

There are also times when the associative property of addition is used, such as a+b+c, where b and c are complements to each other, so you can combine b and c and multiply it with a. If the + in the above equation is changed to x, it can also be easily calculated by using the associative property of multiplication.

The associative law of multiplication.

The associative law of multiplication is also a method of doing simple operations, which is expressed by letters as (a b) c=a (b c), and its definition (method) is: three numbers are multiplied by hand, the first two numbers are multiplied, and then the third number is multiplied; Or multiply the last two numbers first, and then multiply them with the first number of potato fibers, and the product remains unchanged. It can change the order of operations in multiplication operations, and the multiplication law is not used very much in daily life, mainly in some more complex operations to play a simple role.

The commutative law of multiplication.

The multiplicative commutative law is used to swap the positions of individual numbers: a b = b a additive commutative law.

The additive commutative property is used to swap the positions of individual numbers: a+b=b+a, the additive associative law.

a+b）+c=a+（b+c）