This kind of problem is quite difficult for second-grade pupils, and there is nowhere to start. Often primary school students fill in several numbers in a row, all of which are wrong, and it is impossible to determine which answer is correct.

For example:

Let's look at the picture. How much can I fill in the card?

This problem is all a multiplication problem. In fact, it is to prepare pupils for learning division in the future. For example, the first one: () x 6

Let's see, if it is less than 57, what is the maximum number in brackets?

To do this kind of problem, you need to be familiar with the multiplication formula. First, find out who is closest to 57 in the multiplication formula of 6, and we will immediately think of a formula: 6954!

In other words, the maximum number of 9 can be filled in parentheses, because 6 times 9 gets 54, which is the closest to 57, and it also meets the requirement of less than 57. If it is larger, just fill in 10, and the product will be greater than 57, which is obviously not acceptable.

Look at the picture again, the question type is actually the same, and it is also about the maximum number of multiplication.

Here, second-grade pupils must understand arithmetic and methods, so as not to fill in several answers in succession, not sure which is right or wrong.

The correct way is to decimal the numbers after the less than sign in turn until you find the same number as the product of the multiplication formula before the less than sign.

For example, the first () x 9

Therefore, the answer to this math problem is at most 7.

Finally, leave the questions in the picture above to your classmates. Try to do it.