The 20 calculation skills of primary school mathematics are as follows:
1, the pen calculation of two-digit addition, you should remember that three is aligned with the same digit, starting with the single digit, and entering the tenth digit if the digit exceeds 10.
2. Subtract two digits when writing, remember three items, and align the same numbers. If the number of digits is not enough, subtract 1 from the ten digits, add 10 to the one digit and then subtract.
3. Mixed operation calculation rules: in the formula without brackets, only addition and subtraction or only multiplication and division are performed in turn from left to right; In the formula without brackets, if there are multiplication, division and addition and subtraction, multiply and divide first, then add and subtract; If there are brackets in the formula, count the brackets first.
4. Four-digit reading, reading from the high place in turn, thousands, hundreds, and so on. There is a zero or two zeros in the middle, no matter how many zeros there are at the end, don't read them.
5, four-digit writing, starting from the high place, in order, write a few thousands, write a few hundreds, and so on, and write "0" at any one in the middle or at the end.
6, four-digit subtraction should also pay attention to three, the same digit alignment, from the single digit subtraction, which digit is not enough to reduce, from the last digit back to 1, in the standard plus 10 and then reduce.
7. Multiplication rule of multiplying one digit by multiple digits. Starting with single digits, multiply each digit in multiple digits by one digit in turn, and the one with the best product will advance several times.
8. Divider is the division rule of a number. Starting with the high-order division of the dividend, each attempt is made to divide the first digit of the dividend by the divisor. If it is less than the divisor, try to divide the first two digits and write the quotient on that bit. For each quotient, the remaining digits must be less than the divisor.