1, Xiaoming and Xiaohong collect stamps. After Xiaoming gave Xiaohong six stamps, they had the same number of stamps. It turns out that Xiaoming has more stamps than Xiaohong (12).

2. Mr. Wang and Mr. Zhang took 14 children to the park to play 8 games. They want to buy (16) tickets.

Xiaojun traveled abroad with his father. Dad bought a train ticket for 5 yuan, Xiaojun bought half a ticket, and the round trip between them cost (15) yuan.

4. Planting trees on the edge of quadrangular flower beds on Arbor Day. If there are 3 trees on each side, at least (8) trees are needed.

5. Children line up to do exercises, and the red line is in the middle of the team. No matter from top to bottom or from back to front, it is 10. There are (19) children doing exercises in this team.

Extended data:

The concrete application method of mathematical structure in the first grade of primary school;

Many mathematical objects, such as numbers, functions and geometry, reflect the internal structure of continuous operations or the relationships defined in them. Mathematics studies the properties of these structures, for example, number theory studies how integers are represented under arithmetic operations.

In addition, things with similar properties often occur in different structures, which makes it possible for a class of structures to describe their state through further abstraction and then axioms. What needs to be studied is to find out the structures that satisfy these axioms among all structures. Therefore, we can learn abstract systems such as groups, rings and domains.