1. Find patterns for comparison: for example, 594 15 and 6954,79613 and 4936.
2. Tell the story: Tang Priest experienced 81 difficulties, the Monkey King changed in 1992, and Pig Bajie had only half the mana, but changed in 1993.
3. Homonym: My uncle is 81 years old (998 1)
4. Observe the origin of the unit and the tenth place: multiply by nine, the tenth place is negative 1, and the unit is the number on the tenth place MINUS nine, such as 4936.
(1) from big to small, ten from small to big.
Remember four, nine, thirty-six, five and nine. How many can you think of? How much can I consider? Why is this happening? Because they all added 9. It is important for children to understand the relationship between the first sentence and the second sentence!
(2) Grouping rules.