k×k+k× 1/2=2k+ 1/2k

This involves the effective application of elementary mathematics arithmetic, and it is necessary to understand the operation rules to achieve the ideal decomposition calculation effect.

Generally speaking, the calculation order of the four operations is: when there are brackets, calculate the ones in brackets first; When there are no brackets, the second-level operation is calculated first, and then the first-level operation is calculated. When there is only one level of operation, it is calculated from left to right.

First, there are generally five methods for simple operation:

1. rounding method: add and subtract a number to make it an integer ten, an integer hundred and an integer thousand.

2. Intersection method: also known as the law of association, several numbers are added and subtracted, and the positions are exchanged to make up an integer of ten, hundreds and thousands.

3. Method of removing brackets: Sometimes when calculating formulas with brackets, you can simplify the operation by removing brackets, but pay attention to the sign change after removing brackets.

4, the use of operating rules

Additive commutative law: A+B = B+A.

Additive associative law: a+b+c=a+(b+c)

Multiplicative commutative law: a×b=b×a

The law of multiplicative association: a×b×c=a×(b×c)

Multiplication and distribution law: (a+b)×c=a×c+b×c

5. Subtraction property: a-b-c=a-c-b=a-(b+c) Division property: a÷b÷c=a÷c÷b=a÷(b×c)

A. When a calculation problem has only one-level operation (only multiplication and division or only addition and subtraction) and there are no brackets, we can "move with signs" at will.

12.06+5.07+2.94 30.34+9.76- 10.34

25×7×4 34÷4÷ 1.7

102×7.3÷5. 1 4 1.06- 19.72-20.28

7.2+2.2× 1.2 2.6÷ 1.3+8.7

B, when the operation at the same level needs to add brackets or remove brackets, that is, when adding brackets or removing brackets, add a symbol of addition or multiplication in front of brackets, which can be added or removed directly, and add a symbol of subtraction or division in front of brackets. 700÷ 14÷5 18.6÷2.5÷0.4 1.06×2.5×4 5.68+(5.39+4.32) 19.68-(2.97+9.68) 1.25×(8÷0.5)

0.25×(4× 1.2) 1.25×(2 13×0.8)

Three, two typical types of multiplication and distribution laws

A, brackets are addition or subtraction operations, multiplied by another number, pay attention to the distribution. 0.4×(0.25+2.5) ( 12+ 1.2) ×0.2 (40- 1.25)×

B, pay attention to the extraction of the same factor.

0.92× 1.4 1+0.92×8.59 7.8×9.9+9.9×2.2

1.3× 1 1.6- 1.6× 1.3 1 1.9×9.9+ 1. 19× 1

Five, some simple skills

9999+999+99+9 482 1-998

3.2× 12.5×25 1.25×88

3.6×0.25 3.8×9.9+0.38

9.78× 103-9.78×2-9.78 2.6×9.9 0.8