Square area = side length × side length formula S= a×a

Area of rectangle = length× width Formula S= a×b

Area of parallelogram = base× height Formula S= a×h

Trapezoidal area = (upper bottom+lower bottom) × height ÷2 Formula S=(a+b)h÷2

Sum of internal angles: sum of internal angles of triangle = 180 degrees.

Cuboid volume = length× width× height formula: V=abh

Volume of cuboid (or cube) = bottom area × height formula: V=abh.

Volume of cube = side length × side length × side length formula: V=aaa.

Circumference = diameter × π formula: L = π d = 2π r

Area of circle = radius × radius× π formula: s = π R2.

Surface (side) area of cylinder: The surface (side) area of cylinder is equal to the perimeter of bottom multiplied by height. Formula: s = ch = π dh = 2π rh.

Surface area of a cylinder: the surface area of a cylinder is equal to the perimeter of the bottom multiplied by the height plus the area of the circles at both ends. Formula: S=ch+2s=ch+2πr2.

Volume of cylinder: the volume of cylinder is equal to the bottom area multiplied by the height. Formula: V=Sh

Volume of cone = 1/3 bottom× product height. Formula: V= 1/3Sh.

Law of fractional addition and subtraction: Fractions with the same denominator are added and subtracted, only the numerator is added and subtracted, and the denominator remains the same. Add and subtract fractions with different denominators, divide first, then add and subtract.

Multiplication of fractions: use the product of molecules as numerator and the product of denominator as denominator.

Division of fractions: dividing by a number is equal to multiplying the reciprocal of this number.

Reading comprehension will apply the following formulas that define the properties of theorems.

First of all, arithmetic.

1, additive commutative law: Two numbers are added to exchange the position of addend, and the sum is unchanged.

2. The law of addition and association: When three numbers are added, the first two numbers are added first, or the last two numbers are added first, and then the third number is added, and the sum remains unchanged.

3. Multiplication and exchange law: when two numbers are multiplied, the position of the exchange factor remains unchanged.

4. Multiplication and association law: When three numbers are multiplied, the first two numbers are multiplied, or the last two numbers are multiplied first and then the third number, and their products are unchanged.

5. Multiplication and distribution law: When two numbers are multiplied by the same number, you can multiply the two addends by this number respectively, and then add the two products, and the result remains unchanged.

Such as: (2+4) × 5 = 2× 5+4× 5

6. The essence of division: in division, the dividend and divisor are expanded (or reduced) by the same multiple at the same time, and the quotient remains unchanged. Divide o by any number that is not o to get o.

Simple multiplication: multiplication of multiplicand and multiplier, ending with O. You can multiply 1 before o first, and zero does not participate in the operation, and add a few zeros at the end of the product.

7. What is an equation? A formula in which the value on the left of the equal sign is equal to the value on the right of the equal sign.

It's called an equation.

The basic properties of the equation: both sides of the equation are multiplied (or divided) by the same number at the same time,

This equation still holds.

8. What is an equation? A: Equations with unknowns are called equations.

9. What is a linear equation with one variable? A: An equation with an unknown number of one degree is called a one-dimensional linear equation.

Learn the example method and calculation of linear equation of one variable, that is, substitute χ into the formula to calculate.

10, fraction: divide the unit "1" into several parts on average, and the number representing such a part or fraction is called a fraction.

1 1, addition and subtraction of fractions: add and subtract fractions with the same denominator, only add and subtract numerators, and the denominator remains unchanged. Add and subtract fractions with different denominators, divide first, then add and subtract.

12. Fraction comparison: Compared with the denominator, the numerator is large and the numerator is small. Compared with the denominator, the scores of different denominators are divided first and then compared; If the numerator is the same, the denominator is big and small.

13, the fraction is multiplied by the integer, and the numerator is the product of the numerator of the fraction multiplied by the integer, and the denominator remains unchanged.

14, the fraction times the fraction, the numerator is the product of the numerator multiplication, and the denominator is the product of the denominator multiplication.

15, the fraction divided by an integer (except 0) is equal to the fraction multiplied by the reciprocal of this integer.

16, true fraction: the fraction with numerator less than denominator is called true fraction.

17. False fraction: the fraction with numerator greater than denominator or numerator equal to denominator is called false fraction. False score is greater than or equal to 1.

18, with fraction: write false fraction as integer and true fraction, which is called with fraction.

19, the basic nature of the fraction: the numerator and denominator of the fraction are multiplied or divided by the same number at the same time.

(except 0), the score size remains unchanged.

20. A number divided by a fraction is equal to the number multiplied by the reciprocal of the fraction.

2 1, the number A divided by the number B (except 0) is equal to the reciprocal of the number A multiplied by the number B.

1, unit price × quantity = total price 2, single output × quantity = total output.

3, speed x time = distance 4, efficiency x time = total work.

5. Appendix+Appendix = and one addend = and+another addend

Negative-negative = differential negative = negative-differential negative = negative+difference.

Factor × factor = product One factor = product ÷ another factor.

Frequency divider/frequency divider = frequency divider = frequency divider/frequency divider = quotient × frequency divider

Division with remainder: dividend = quotient × divisor+remainder

A number is continuously divided by two numbers. You can multiply the last two numbers first and then divide this number by their product. The result remains the same. Example: 90 ÷ 5 ÷ 6 = 90 ÷ (5× 6).

6. 1 km = 1 km 1 km =1000m

1 m = 10 decimeter 1 decimeter =10 cm1cm =10 mm.

1 m2 = 100 square decimeter 1 square decimeter = 100 square centimeter

1 cm2 = 100 mm2

1 m3 = 1000 cubic decimeter

1 cm3 = 1000 cm3

1 ton = 1 000kg1kg = 1 000g = 1 kg =1kg.

1 hectare = 1 10,000 square meters. 1 mu = 666.666 square meters.

1 liter = 1 cubic decimeter = 1000 ml 1 ml = 1 cubic centimeter.

7. What is the ratio? Divided by two numbers is called the ratio of two numbers. Such as 2÷5 or 3:6 or 1/3.

The two items before and after the ratio are multiplied or divided by the same number at the same time (except 0), and the ratio remains unchanged.

8. What is proportion? Two formulas with equal ratios are called proportions. For example, 3: 6 = 9: 18.

9. Basic properties of proportion: In proportion, the product of two external terms is equal to the product of two internal terms.

10, solution ratio: Find the unknown term in the ratio, which is called solution ratio, such as 3: χ = 9: 18.

1 1, ratio: two related quantities, one changes and the other changes. If the corresponding ratio (i.e. quotient k) of these two quantities is certain, these two quantities are called proportional quantities, and their relationship is called proportional relationship. Such as y/x=k( k is certain) or kx.

12, inverse ratio: two related quantities, one of which changes and the other changes accordingly. If the product of the corresponding two numbers in these two quantities is certain, these two quantities are called inverse proportional quantities, and their relationship is called inverse proportional relationship. For example, x x×y = k( k is certain) or k/x = y.

Percentage: a number that indicates that one number is a percentage of another number, which is called percentage. Percent is also called percentage or percentage.

13. To convert a decimal into a percentage, just move the decimal two places to the right and add hundreds of semicolons after it. In fact, to convert a decimal into a percentage, just multiply this decimal by 100%.

To convert percentages to decimals, simply remove the percent sign and move the decimal point two places to the left.

14. To convert a fraction into a percentage, generally, first convert the fraction into a decimal (except when it is used up, three decimal places are generally reserved), and then convert the decimal into a percentage. In fact, to convert a fraction into a percentage, you need to convert it into a decimal and then multiply it by 100%.

The percentage is converted into a component number. First, the percentage is rewritten into a component number, and the divisible quotation is made into the simplest score.

15. Learn how to turn fractions into fractions and how to turn fractions into decimals.

16, greatest common divisor: several numbers can be divisible by the same number at the same time, and this number is called the greatest common divisor of these numbers. (or the common divisor of several numbers is called the greatest common divisor of these numbers. The largest one is called the greatest common divisor. )

17, prime number: the common divisor is only 1 two numbers, which is called prime number.

18, least common multiple: the common multiple of several numbers is called the common multiple of these numbers, and the smallest is called the least common multiple of these numbers.

19. Comprehensive score: the score converted from different denominators to the same denominator is equal to the original score, which is called comprehensive score. (Generally, the score is the least common multiple. )

20. Decreasing score: When a score is equal to it, but both numerator and denominator are small, it is called declination.

2 1, simplest fraction: The fraction whose numerator and denominator are prime numbers is called simplest fraction.

At the end of the score calculation, the score must be converted into the simplest score.

Numbers in units of 0, 2, 4, 6 and 8 can be divisible by 2, that is, they can be binary.

Deadline. A number with a bit of 0 or 5 can be divisible by 5, that is, it can be divisible by 5. Pay attention to use when cutting.

22. Even and odd numbers: Numbers divisible by 2 are called even numbers. Numbers that are not divisible by 2 are called odd numbers.

23. Prime number (prime number): If a number only has 1 and its two divisors, it is called a prime number (or prime number).

24. Composite number: A number is called a composite number if it has other divisors besides 1 and itself. 1 is neither prime nor composite.

28. Interest = principal × interest rate × time (time is generally in years or months, which should correspond to the unit of interest rate).

29. Interest rate: The ratio of interest to principal is called interest rate. The ratio of interest to principal within one year is called annual interest rate. The ratio of interest to principal in January is called monthly interest rate.

30. Natural number: an integer used to represent the number of objects, called natural number. 0 is also a natural number.

3 1, Cyclic Decimal: A decimal, in which one or more numbers are repeated from a number in the decimal part. Such decimals are called cyclic decimals. Like 3. 14 14 14.

32. Acyclic decimal: a decimal, starting from the decimal part, without one number or several numbers appearing in turn repeatedly. Such a decimal is called an acyclic decimal.

Like 3. 14 1592654.

33. Infinitely circulating decimal: a decimal, from the decimal part to the infinite digits, is called an infinitely circulating decimal without one or several numbers repeating in turn. Like 3. 14 1592654 ...

34. What is algebra? Algebra is to replace numbers with letters.

35. What is algebraic expression? Expressions expressed in letters are called algebraic expressions. For example, 3x =(a+b