Math diary 1 night during the winter vacation of grade one, I saw a difficult problem in the book of Olympic Mathematics: the number of apple trees in the orchard is three times that of pear trees. Master Lao Wang fertilizes 50 apple trees and 20 pear trees every day. A few days later, all the pear trees were fertilized, but the remaining 80 apple trees were not fertilized. Excuse me: How many apple trees and pear trees are there in the orchard?

I am not intimidated by this question, but it can stimulate my interest. I think the apple tree is three times as big as the pear tree. If two kinds of trees are to be fertilized on the same day, Master Lao Wang will fertilize "20×3" apple trees and 20 pear trees every day. In fact, he only fertilizes 50 apple trees every day, which is 10, and the last 80 trees. Therefore, Master Lao Wang has been fertilizing for 8 days. 20 pear trees a day, 8 days is 160 pear trees. According to the first condition, there are 480 apple trees. This is to solve the problem with hypothetical thinking, so I think the hypothetical method is really a good way to solve the problem.

Today, I know RMB, including 100 yuan, 50 yuan, 20 yuan, 10 yuan, 5 yuan, 2 yuan, 1 yuan, 50 points, 20 points, 65,438 points, 5 points, 2 points, 1 minute. I know the face value of RMB. There are five RMB 10 in 50 yuan, and five RMB 1 is 50, 1 = 10, 1 = 10. I also know that there are two kinds of RMB, one is paper money and the other is coins.

We should not scribble on the RMB, but cherish it. Save money from an early age, don't misuse it, and form good habits.

For the majority of primary school students, winter vacation should be happy and full.