How to learn how to find defective products and how to draw pictures.

The problem of finding defective products is regular.

Generally, it is divided into three parts: A, A and B. B can be equal to A, and B may also be equal to a+ 1 or a- 1, depending on the total number.

Put two A's at both ends of the balance. If the balance is balanced, the defective product is in B; If the balance is unbalanced, find out which is the defective product according to the difference between the defective product and the genuine product.

After finding it, continue to divide it into three parts.

This can eliminate two-thirds at a time, which is the fastest.

1 turn to 3, and it will be done in one go.

4-9, twice.

10-27. It takes three times.