1, normalization problem

2. The problem of induction

3. Sum and difference problem

4, and the times.

5, the problem of differential time

Step 6 double the problem

7. Meeting issues

8. Catch up with the problem

9. Planting trees

10, age problem

1 1, navigation problem

12, train problem

13, clock problem

14, profit and loss problem

15, engineering problems

16, positive-negative ratio problem

17, distributed in proportion

18, percentage problem

19, the problem of "cattle eating grass"

20. The cage problem of chickens and rabbits

2 1, square matrix problem

22, commodity profit problem

23, deposit interest rate problem

24, solution concentration problem

25, composition number problem

26. Magic Square Problem

27, pigeonhole principle problem.

28. Equality in the Convention.

29. The most important issue

30, column equation problem