Olympus

Topic: 1. A, B, and C each took out 9 yuan to buy a batch of exercise books. Since B has more than 15 books, C and B take the same amount, so B and C must be given to A. 1.5 yuan, then, how many exercise books did the three bought?

Answer from the answerer: There are difficulties! Why not come here simple? depressed!

Answer method: Since B has taken 15 more than A, and C and B take the same amount, you can know that there are 3 times plus a total of 30. On average, each person has a number of +10. These are straight for 9 yuan. A, the number of people who take the average is 10 less than the average, so it should be less, he is less than 1.5 * 2 = 3 yuan. So 10 books are 3 yuan straight. 0.3 yuan per book. The three bought 3*9/0.3=90 copies.

After the answer: I finally got it, is there a reward?

Topic: Zhang, Wang, Li, Zhao, four people play table tennis, every two people have to play one game. As a result, Zhang Sheng had Zhao, and Zhang, Wang, and Li won the same number of games. How many times did Zhao win?

Answer from the answerer: Work hard, fight for it!

Answer method: You can know that each person has 3 games and a total of 6 games. That is, there are 6 victories. Zhang Sheng had Zhao, and Zhang, Wang, and Li won the same number of matches, indicating that Zhang, Wang, and Li won three games, or two games. First look at the situation of three people winning a game, they won three games together, the game has a total of six games, then Zhao will win three games, but he did not win, contradictions, not established. Look at 3 people each win 2 games, there are always a total of 6 games, then Zhao wins 0 games.

After the answer: Oh, I am smart!

Topic: 1. Write the 2005 natural numbers from 1 to 2005 in order to get a multi-digit number 123456789. . . . . In 2005, what is the multi-digit number divided by 9?

Answerer's testimony: I am dizzy!

Answer method: First, study the characteristics of numbers that can be divisible by 9: if the sum of the digits on each digit can be divisible by 9, then the number can be divisible by 9; if the sum of the digits cannot be divisible by 9, then The remainder is the remainder of this number divided by 9.

Problem Solving: 1+2+3+4+5+6+7+8+9=45; 45 can be divisible by 9 and so on: 1~1999 The sum of the digits of the digits of these numbers can be divisible by 9

10~19, 20~29...90~99 The number of the ten digits in these numbers has appeared 10 times, then the sum of the digits on the ten digits is 10+20+30+...+90=450 Divided by 9 for the same reason, the sum of the digits on the 100~900 hundred digits is 4500 and is also divisible by 9

The sum of the digits of 200020012002200320042005 is 27, which is also just divisible. The final answer is that the remainder is zero.

After the answer: I want to rest! Mom: No! 555555555555555555~~~~~~~~~~~~~