Give a simple example: 12× 2 = 24. The method of multiplication check is to exchange the two multipliers and recalculate to see if the results of the two multiplications are the same, that is, 2× 12 = 24. The method of division check is to divide the product by one of the multipliers to see whether the quotient is another multiplier, that is, 24 ÷ 2 = 12 or 24 ÷ 12 = 2.
Simple multiplication operation
First, the combination method
A number multiplied by two one-digit numbers can be rewritten as the product of this number multiplied by these two numbers according to the situation, which makes the calculation simple. When calculating, adding a bracket can make the calculation simple. Because there is a multiplication symbol in front of the brackets, there is no symbol in the brackets.
Second, the decomposition method
A number multiplied by a two-digit number can be decomposed into two one-digit multiplication forms according to the situation, and then this number is multiplied by two one-digit numbers continuously, so the calculation is simple.
Third, the split number method
Some problems, if calculated step by step, will be more troublesome. According to the characteristics of factors and other numbers, we can flexibly use factorization to make simple calculations.
Fourth, the number change method
Some topics can be converted into some numbers according to the situation, creating conditions to simplify the complex.