Write two-digit addition first, and remember three things.
1, aligned with the same number;
2. Starting from the unit;
3. When the number of digits reaches 10, enter 1 into ten digits.
Second, write down the subtraction of two digits 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.
Third, the mixed operation algorithm
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.
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.
Five-digit or 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.
Six or 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.
Seven, one-digit multiplication by multi-digit multiplication rules
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.
Divider is the division rule of a number.
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.
Nine, a factor is the multiplication rule of two digits.
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.
Ten, divisor 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.
Eleven, ten thousand people series reading rules
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.
Twelve, 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.
Thirteen. Decimal size comparison
Compare the sizes of two decimals, first look at their integer parts, and the integer parts are larger. That number is large, the integer part is the same, the number with the largest decimal place is large, the decimal place is the same, the number with the largest decimal place is large, and so on.
Fourteen, decimal addition and subtraction operation rules
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.
Fifteen, the calculation rules of decimal 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.
Sixteen, divisor 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.
Seventeen, divisor is a decimal division algorithm.
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.
Eighteen, 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.
Nineteen, the general steps of solving application problems with column equations
1, find out the meaning of the problem, find out the unknown, and express it with x;
2. Find out the equal relationship between the quantities in the application problem and make an equation;
3. Solve the equation;
4. Test and write the answers.
Twenty, 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.
Twenty-one, the same denominator and the same fraction addition and subtraction
To add and subtract fractions, first add and subtract the integer part and the fraction part respectively, and then combine the obtained numbers.
Twenty-two, the addition and subtraction of different denominator fractions
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.
Twenty-three, the calculation rules of decimal times integer
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.
Twenty-four, the score multiplied by the score calculation rules
Fractions are multiplied by fractions, the product of numerator multiplication is numerator, and the product of denominator multiplication is denominator.
Twenty-five, a number divided by a fraction calculation rules
A number divided by a fraction is equal to the number multiplied by the reciprocal of the divisor.
Twenty-six, 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.
Twenty-seven, fraction into percentage and percentage into number method.
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.