Monday
Monday: Area models and partial products
Lucy the Ladybug waves from a big daisy at the edge of the garden.
Bennie the Bear is planning a sunflower patch with 34 rows and 26 plants in each row.
"How many sunflowers is that?" asks Lucy. "Those numbers feel big. I feel a little nervous."
"It is okay to feel nervous," says Bennie. "Let us take one slow breath together."
"Then we break the big problem into small, friendly pieces."
Lucy breathes in and out. Her seven spots seem to relax.
"Friendly pieces," she says. "I can do that!"
Learn it: break the factors apart
Think of 34 × 26 as a rectangle 34 long and 26 wide.
Break 34 into 30 + 4. Break 26 into 20 + 6.
That cuts the rectangle into four smaller parts.
30 × 20 = 600
30 × 6 = 180
4 × 20 = 80
4 × 6 = 24
Add the partial products: 600 + 180 + 80 + 24 = 884.
So Bennie plants 884 sunflowers.
The same idea works on a small grid.
6 × 12 = 6 × 10 + 6 × 2 = 60 + 12 = 72.
- Read the question.
- Tap your answer.
- Read the question.
- Tap your answer.
- Read the question.
- Tap your answer.
| Sentence | True or false? |
|---|---|
| 34 × 26 = 600 + 180 + 80 + 24 | ? |
| 25 × 12 = 200 + 40 + 50 + 10 | ? |
| 6 × 12 = 6 × 10 + 6 × 2 | ? |
| 43 × 21 = 800 + 4 + 60 + 3 | ? |
Outline a rectangle 12 squares long and 14 squares wide.
Mark a line to split 14 into 10 and 4.
Find each part, then add to get 12 × 14.
Brave work with big numbers! Tomorrow we learn the standard algorithm.