2. Single output × quantity = total output

3. Speed × time = distance

4. Work efficiency x time = total workload.

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

Minus-Minus = Differential Minus = Minus-Differential Minus = Minus+Differential Factor× Factor = Product of one factor = Product of another factor.

Divider/Divider = quotient divisor = dividend/quotient dividend = quotient x divisor divided by remainder: dividend = quotient x divisor+remainder

A number is divided by two consecutive numbers. You can multiply the last two numbers first, and then divide this number by their product, and the result is still the same. For example: 90 ÷ 5 ÷ 6 = 90 ÷ (5× 6)

1km = 1km 1km = 1000m 1m = 10DM 1DM = 10cm 1cm = 10mm 65448。 100 square centimeter 1 square centimeter = 100 square millimeter 1 cubic meter = 1000 cubic centimeter 1 cubic centimeter/cubic centimeter/cubic centimeter. 1k g = 1000g = 1k g 1ha = 10000 m2。 1 mu = 666.666 square meters 1 liter = 1 decimeter cubic = 1000 ml 1 ml = 1 cubic centimeter second, arithmetic.

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

2. Law of additive combination: 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. a+b+c=a+(b+c)

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

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. a x b+a x c=a x(b+c)

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. Nature 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. O is divided by any number that is not O. Simple multiplication: the multiplicand and the end of the multiplier are multiplied by 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: when the same number is added (or subtracted) on both sides of the equation, the equation still holds; When both sides of the equation are multiplied (or divided) by the same number (except zero), the equation still holds. 8. Score: Divide the unit "1" into several parts on average, and the number representing such a part or points is called a score.

9. Addition and subtraction of fractions: add and subtract fractions with denominator, only add and subtract numerators, and the denominator remains unchanged. Fractions of different denominators are added and subtracted, first divided, then added and subtracted.

10, comparison of fraction size: Compared with the fraction of denominator, the numerator is large and the numerator is small. Compare the scores of different denominators, divide them first and then compare them; If the numerator is the same, the denominator is big and small.

1 1. The fraction is multiplied by an integer, and the product of the multiplication of the fraction and the integer is the numerator, and the denominator remains unchanged. 12, the fraction is multiplied by the fraction, the product of molecular multiplication is the numerator, and the product of denominator multiplication is the denominator.

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

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

15. 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. 16, with fraction: write the false fraction as an integer, and the true fraction is called with fraction.

17, 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), and the size of the fraction remains unchanged.

18, a number divided by a fraction is equal to this number multiplied by the reciprocal of this fraction. 19, the number A divided by the number B (except 0) is equal to the reciprocal ratio and percentage of the number A multiplied by the number B.

1, what is ratio: dividing two numbers is called the ratio of two numbers. For example, the first and second terms of the ratio of 2÷5 or 3:6 or 1/3 are multiplied or divided by the same number at the same time (except 0), and the ratio remains unchanged.

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

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

4. Solution ratio: The unknown term in the ratio is called solution ratio. Such as 3: χ = 9: 18.

5. Proportion: two related quantities, one of which 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 the relationship between them is called proportional relationship. For example: y/x=k( k must be) or kx = y 6, inverse ratio: two related quantities, one of which changes and the other changes. 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×y = k( k must be) or k/x = y percentage: a number indicating that one number is a percentage of another number is called a percentage. Percentages are also called percentages or percentages.

7. To convert decimals into percentages, just move the decimal point two places to the right and add hundreds of semicolons at the back. 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.

8. Turn the score into a percentage. Usually, the fraction is converted into a decimal (three decimal places are usually reserved when it is not used up), and then the decimal is converted into a percentage. In fact, to turn a fraction into a percentage, you must first turn the fraction into a decimal and then multiply it by 100%. Divide the percentage into components, and rewrite the percentage into components first, so that the quotation that can be lowered can be made into the simplest score.

We must learn decimal numbers and decimals.

10, 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 common divisor of these numbers. The largest one is called the greatest common divisor. )

1 1, prime number: the common divisor is only 1, which is called a prime number.

12, least common multiple: the multiple shared by several numbers is called the common multiple of these numbers, and the smallest is called the least common multiple of these numbers.

13. Comprehensive score: changing scores of different denominators into scores of the same denominator is equal to the original score, which is called comprehensive score. (Generally, the least common multiple is used for division) 14. Simplification: It is called simplification to change a fraction into a fraction equal to it but with a smaller denominator. (The greatest common divisor is used for divisor)

15, 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 all be divisible by 2, that is, they can be subtracted by 2. A number with a bit of 0 or 5 can be divisible by 5, that is, it can be subtracted by 5. Pay attention to the use of contracts.

16, even number and odd number: Numbers divisible by 2 are called even numbers. Numbers that are not divisible by 2 are called odd numbers.

17, prime number (prime number): If a number only has 1 and two divisors of itself, it is called a prime number (or prime number).

18, composite number: a number. If there are other divisors besides 1 and itself, such numbers are called composite numbers. 1 is neither prime nor composite. 19, interest = principal × interest rate× time (time is usually in years or months, which should correspond to the unit of interest rate).

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

2 1, natural number: an integer used to represent the number of objects, called natural number. 0 is also a natural number.

22. Cyclic decimal: A decimal in which one or more numbers are repeated from a certain position in the decimal part. Such decimals are called cyclic decimals. Like 3. 14 14 14.

23. Acyclic decimals: Decimals that start from the decimal part without one or several numbers appearing in turn repeatedly. Such a decimal is called an acyclic decimal. Like 3.

24. Infinitely circulating decimal: a decimal, from the decimal part to the infinite digits, is called infinitely circulating decimal without one number or several numbers appearing repeatedly. Like 3.

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

26. What is algebraic expression? Expressions expressed in letters are called algebraic expressions. For example 3x = AB+C.