Master the art of multiplying two-digit numbers with regrouping! Learn to handle multiple regrouping steps with confidence and accuracy.
Library Book Purchase Challenge! The school library is buying new books for the reading program. Each box contains 28 books, and they need to order 15 boxes. How many books will the library receive in total? Let's solve this using the powerful area model method!
The area model represents multiplication as the area of a rectangle. We break down each number into its tens and ones, then create a grid to show all the partial products.
Think of it like this: It's like dividing a rectangle into smaller rectangles, where each smaller rectangle represents a part of the multiplication!
Break down 28:
28 = 20 + 8
Break down 15:
15 = 10 + 5
28 (20 + 8) × 15 (10 + 5)
In this example, we don't have regrouping in the final addition, but let's look at a case where we do:
Notice: 26 × 8 = 208 (regrouping needed)
Answer: 34 × 16 = 544
Note: 27 × 9 = 243 (regrouping: 7×9=63, write 3, carry 6)
Answer: 27 × 19 = 513
Create an area model for 25 × 17:
A store has 23 shelves, and each shelf holds 18 items. How many items are there in total?
When a product is 10 or more, remember to carry the tens digit to the next column.
When multiplying by the tens digit, shift the result one place to the left.
Double-check your addition when combining all the partial products.
A factory produces 36 items per hour and operates for 14 hours. How many items are produced in total?
Use the vertical algorithm to solve: 29 × 17