First, for the calculation of addition, subtraction, multiplication and division, the check calculation is usually realized by reverse calculation. For example, for an addition formula "23+ 15=38", we can verify its correctness by subtraction, that is, "38- 15=23". Similarly, for a multiplication formula "7×6=42", we can verify its correctness by division, that is, "42÷6=7".

Secondly, for the correctness of the formula, the checking calculation is usually realized by substituting numerical values. For example, in a formula "2x+3=7", we can substitute the value of x into the calculation, that is, "2x2+3 = 7". If the equation holds, the correctness of the formula is verified.

In addition to the above two methods, sometimes we need to use other methods to check. For example, for the calculation of scores, "? +? =5/ 12 ",we can use the general score to verify, that is," 4/6+3/12 = 8/12+12 = 9/1.

In a word, primary school mathematics examination is a very important link, which can help students check the accuracy of calculation and improve their mathematics application ability. We can effectively verify the correctness of addition, subtraction, multiplication, division and formulas through reverse calculation, numerical substitution and general division.

Basic introduction

Addition checking is a method to check whether the addition operation is correct. The checking method of addition is as follows: double checking algorithm (recalculate the original formula again. If the results of the two calculations are the same, the calculation is correct). In addition, there are addition check, subtraction check and discard nine check.

Addition checking refers to the method of checking whether the process and result of addition operation are correct. Addition checking is a method to check whether the addition operation is correct. The calculation method of addition is as follows: According to additive commutative law, after exchanging the positions of addends, add them again. If the results of the two calculations are the same, the original calculation is correct.