Idea 16of 24Builds onThe area model for 23 × 14
Partial products in a column
How do you write the area model without drawing it?
Today you'll discover
- one line for each part
- why the place values matter
- how the column adds up
Think first23 × 14, written in a column
Written in a column, 23 × 14 starts with 3 × 4 = 12. What is the next line, 20 × 4?
Decide first, then press Next. Match each line to a part of the rectangle.
23 × 14 written in a column. Four lines appear under it: 12 for 3 × 4, 80 for 20 × 4, 30 for 3 × 10 and 200 for 20 × 10. Then 47 × 18 the same way, 56, 320, 70 and 400, adding to 846. The last step shows 62 × 19.
See the whole ideathe big idea and the key word, in one place
The big idea
Each line of the column is one partial product, one part of the area model.
23 × 14, line by line
Four lines, then the total.
- 3 × 412
- 20 × 480
- 3 × 1030
- 20 × 10200
- total322
Easy to get wrongLine the digits up by place: ones under ones, tens under tens, hundreds under hundreds.
Key word
- partial product
- the product of one part of each factor, like 20 × 4 = 80 in 23 × 14
Ready to use it?
- Write the four partial products in a column.
- Add the partial products to find the product.