1, remember large numbers in your mind, and count decimal numbers up. 5+2=7, 5 is a big number, remember 5. 2 is a decimal. Add up the numbers 6 and 7 and the result is 5+2=7.

2, one plus nine, ten tadpoles, two plus eight, ten old ducks, three plus seven, ten old hens, four plus six, ten golden monkeys, five plus five, and ten big tigers.

3. See 1 and think of 9, 2, 8, 3, 7, 4, 6, 5, 5, 6, 1, 7, 3, 8, 2, 9 and 1.

4, 2 can be divided into 1 and 1, 3 can be divided into 1 and 2,2 and 1, 4 can be divided into 1 and 3,2 and 2,3 and 1, and 5 can be divided into 1.

5. See 9 and think of1; When you see 8, you think of 2; When you see 7, you think of 3; When you see 6, you think of 4; When you see 5, you think of 5; When you see the big corner decimal system, change two numbers first.