Generally, look at the horizontal figures first, and then look at the vertical figures. Notice that there is a comma in the middle.
2. The meaning of fractional multiplication: a number times a fraction, such as 4 times, which means: What is the number of 4?
Fraction × A number such as ×4 means: What is four times the solution?
3. Two numbers whose product is 1 are reciprocal. The reciprocal of 1 is 1 0 without reciprocal.
4. dividing by a number that is not equal to 0 is equal to multiplying the reciprocal of this number.
Division of two numbers is also called the ratio of two numbers. The ratio is usually expressed in fractions, and can also be expressed in fractions or integers.
6. The basic nature of the ratio: the first term and the second term of the ratio are multiplied or divided by the same number at the same time (except 0), and the ratio remains unchanged.
7. The ratio of the circumference to the diameter of a circle is called pi, which is expressed by Wu, and Wu ≈ 3.438+04.
8. About the formula of circle:
C= d = 2 r S = r 2。
d = c÷d = 2 r r = d÷2 r = c÷2
The area of the ring S =σR2-σR2.
9. Original price × discount = current turnover × tax rate = tax payable × principal × interest rate × time = interest.
Interest tax = principal × interest rate× time× 20% or interest tax = interest× 20%.
After-tax interest = principal × interest rate × time × (1-20%) or after-tax interest = interest × (1-20%)
How much can I get back after paying taxes = principal+principal × interest rate× time × (1-20%).
10. Bar chart: How much data can be seen clearly.
Broken-line statistical chart: you can clearly see the trend of data increase and decrease (generally related to time).
Department statistical chart: you can clearly see the relationship between each part and the whole.