1. math diary Fan Wen, a second-grade pupil.

Grandpa took out a dirty calendar today, and some dates were unclear. Let me help him figure out what day the 27th is, because it's grandma's birthday. I looked at the calendar. It's too simple. The 22nd is Saturday, so 27-22=5, and the 27th is not Thursday. At this moment, my father is right. Let me try something else.

So I began to think again: the 2nd is Sunday, and the difference from the 27th is 27-2=25 days, a week is 7 days, and 25÷7=3 (weeks) ... 4 (days), so I can also conclude that the 27th is Thursday. By the way, dad smiled and said, "You are great! Any clearly visible number can be calculated, and mathematics in life can be seen everywhere. "

2. math diary Fan Wen, a second-grade pupil.

Today, the teacher taught us "the basic nature of comparison".

"The basic property of ratio" is similar to "the basic property of fraction". The two items before and after the ratio are multiplied or divided by the same number at the same time, and the ratio remains unchanged except 0. This is not groundless!

The ratio of 16: 4 is 4, and the ratio of 4: 1 is also 4. Take a closer look at the two sets of numbers. 16 to 4 is divided by 4, and 4 to 1 is divided by 4, that is to say, "the first term and the last term of 16: 4 are divided by 4 at the same time", and the ratio is still 4, so conversely, 4 to 16 is multiplied by 4, and 1 4 is also divided.

This can be seen from this example. So we come to the conclusion that the two terms before and after the ratio are multiplied or divided by the same number at the same time, except for 2 and 0, the ratio remains unchanged.

However, it should be noted that the first item and the last item must be "simultaneous". If the first item is multiplied first and the last item is multiplied again, it will not work; It must also be "the same number". If it is not the same number, one times 3 and one times 4, it will be even worse; Of course, it will rule out 0!

3. math diary Fan Wen, a second-grade pupil.

The first class this morning is math, and the teacher is going to tell us the division formula.

A classmate demonstrated on the blackboard, "She explained the formula of dividing three digits by one digit for a while." I don't understand one thing, so I raised my hand and stood up and asked, "Why do three digits divide by one digit, sometimes the quotient is two digits, and sometimes it is three digits?"

This is a classmate who raised his hand and stood up to answer: "because one percent of the number is divided by a few hours, the quotient is double digits." If the number on the hundredth bit is greater than or equal to the divisor, the quotient is a three-digit number.

At first, my classmates and I have been arguing about it. It was not until later that he demonstrated several formulas on the blackboard that he persuaded me. Although I lost, I figured out a math problem and the secret of the division formula.