Unit 4 "Three Numbers Multiply Two Numbers". Example 4 On the basis of students' understanding of the model of "unit price × quantity = total price" in grade three, the related concepts and models are formally given by combining multiplication operation.

2. Unit 6 "Divider is the division of two digits", using the variant model of multiplication model: total price ÷ quantity = unit price, total price ÷ unit price = quantity, distance ÷ time = speed.

3. 108 page math game, this kind of problem can be solved by division model with remainder.