1, aligned with the same number;

2. Starting from the unit;

3. When the number of digits reaches 10, enter 1 into ten digits.

(2) Do a two-digit subtraction with a pen, and remember three things.

1, aligned with the same number;

2. Reduce from one place;

3. If the number of digits is not enough, subtract 1 from the number of digits, add 10 to the number of digits and then subtract.

(3) Calculation rules of mixed operation

1, in the formula without brackets, only addition and subtraction or multiplication and division can be performed from left to right;

2. In the formula without brackets, if there are multiplication and division and addition and subtraction, the multiplication and division should be calculated first, and then the addition and subtraction should be calculated;

3. If there are brackets in the formula, count the brackets first.

(4) Four-digit pronunciation

1, read in order from the high order, thousands, hundreds, and so on;

2. There is a zero or two zeros in the middle, and only one "zero" is read;

No matter how many zeros there are, don't read the last number.

(5) Four-digit writing

1, written in order from the high order;

2. Write a few words in thousands, a few words in hundreds, and so on. Write "0" in the middle or at the end.

(6) Four-digit subtraction should also pay attention to three items.

1, aligned with the same number;

2. Reduce from one place;

3. Which figure is not enough to reduce? Retract 1 from the previous position, add 10 to the standard position, and then subtract.

(7) Multiplication rule of one-digit multiplication by multi-digit multiplication

1, starting from the unit, multiply each digit in multiple digits by one digit in turn;

Whoever gets the highest score will be promoted several times.

(8) Divider is the division rule of single digits.

1. Divide the dividend by the first digit of the dividend every time starting from the high digit of the dividend. If it is less than the divisor, try the division of the first two digits again.

2. Write the quotient where the divisor is divided;

3. For each quotient, the remainder must be less than the divisor.

(9) A multiplication rule in which one factor is a two-digit number.

1, first multiply the number on the two-digit number by another factor, and the last digit of the number is aligned with the two-digit number;

2. Multiply the number on the ten-digit number by another factor to get that the last digit of the number is aligned with the ten-digit number;

3. Then add up the multiplied numbers twice.

(10) Divider is the division rule of two digits.

1. Starting from the high order of the dividend, try to divide the first two digits of the dividend by the divisor. If it is less than the divisor,

2. Write the business on any one except the bonus;

3. For each quotient, the remainder must be less than the divisor.

The reading rules of (1 1) ten thousand people series

1, read ten thousand levels first, and then read one level;

2, 10,000-level numbers should be read according to the ten-level reading method, and then add a word "10,000" at the back;

3. Don't read the last digit of each level, no matter how many zeros there are. Other numbers have a read-only "zero" with one zero or several consecutive zeros.

(12) Multi-digit reading rules

1, starting from the high position and reading down one level at a time;

2. When reading 100 million or 10,000 levels, read according to a series of reading methods, and then add the words "100 million" or "10,000" at the back;

3. Don't read the zero at the end of each level, other numbers have a zero, or read only one zero for several consecutive zeros.

Comparison of (13) decimal sizes

Compare the sizes of two decimals, first look at their integer parts. The number with large integer parts is large, so is the number with large integer parts, the number with large decimal places is large, the number with large decimal places is also large, and so on.

(14) decimal addition and subtraction algorithm

To calculate decimal addition and subtraction, first align the decimal point (that is, align the numbers on the same digit), then calculate by integer addition and subtraction, and finally align the decimal point position on the horizontal line and point the decimal point.

(15) Calculation Rules of Fractional Multiplication

To calculate decimal multiplication, first calculate the product according to the multiplication law, then look at the decimal places in the factor, count the decimal places from the right side of the product and point to the decimal point.

(16) The divider is the law of integer division.

Dividers are fractional divisions of integers. Divide according to the law of integer division. The decimal point of quotient should be aligned with the decimal point of dividend. If there is a remainder at the end of the dividend, add 0 to the remainder and continue the division.

(17) Division algorithm with divisor as decimal.

Divider is the division of decimals. First, move the divisor decimal point to make it an integer. The decimal point of the divisor is shifted to the right by several digits, and the decimal point of the dividend is also shifted to the right by several digits (the digits are not enough to make up the 0 at the end of the dividend), and then it is calculated by fractional division with the divisor as an integer.

(18) Steps to Solve Application Problems

1, find out the meaning of the problem, find out the known conditions and problems, analyze the quantitative relationship in the problem, and determine what to calculate first, then what to calculate, and finally what to calculate;

2. Determine how to calculate each step, list formulas and work out numbers;

3. Test and write the answers.

General steps of solving application problems with (19) series equation

1, find out the meaning of the problem, find out the unknown, and express it with x;

2. Find out the equal relationship between quantity and quantity in the application problem and make the equation;

3. Solve the equation;

4. Test and write the answers.

(20) Addition and subtraction of fractions with the same denominator

Add and subtract fractions with the denominator, the denominator remains the same, and only the numerator is added and subtracted.

(2 1) Addition and subtraction with fractions in the same denominator

To add and subtract fractions, first add and subtract the integer part and the fraction part respectively, and then combine the obtained numbers.

(22) Addition and subtraction of fractions with different denominators

The addition and subtraction of fractions with different denominators are divided first, and then calculated according to the addition and subtraction law of fractions with the same denominator.

(23) Calculation rules for multiplying fractions by integers

Multiply a fraction by an integer, and use the product of the numerator of the fraction multiplied by the integer as the numerator, with the denominator unchanged.

(24) Rules for calculating the score multiplied by the score

Fractions are multiplied by fractions, the product of numerator multiplication is numerator, and the product of denominator multiplication is denominator.

(25) Calculation rules for dividing a number by a fraction

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

(26) Decimal into percentage and percentage into decimal method.

To convert decimals into percentages, just move the decimal point two places to the right, followed by hundreds of semicolons;

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

(27) Methods of converting fractions into percentages and converting percentages into component numbers.

To turn a fraction into a percentage, usually first turn the fraction into a decimal (except for three decimal places), and then turn the decimal into a percentage;

Convert percentages to decimals. First, rewrite the percentage into a fraction with the initials 100, and make a quotation that can be turned into the simplest fraction.