Area model for multiplication and fractions v0.1.0
×
10420
200
80
330
12
20 × 10 = 200
20 × 4 = 80
3 × 10 = 30
3 × 4 = 12
Add them up: 200 + 80 + 30 + 12 = 322
23 × 14 = 322
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Type two numbers and the rectangle is split by place value, with every partial product and the sum. Or shade a grid to see a fraction of a fraction.
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How to use it
- Type two whole numbers from 1 to 99.
- Read the four boxes: each is the tens or ones of one number times the tens or ones of the other.
- Add the boxes. Turn on “Hide the products” to let students fill them in first.
- For fractions, open “A fraction of a fraction” and tap the grid: blue is the across fraction, yellow the down, green their product.
Ideas for class
- Do 23 × 14 and ask which box is biggest and why.
- Hide the products, have students work in pairs, then show them to check.
- Compare with the standard algorithm: which partial product is each line of the old way?
- Try 40 × 30, where only one box has a value, and talk about the zeros.
- Shade 2/3 across and 3/4 down and say what part of the whole is green.
- Print the page and have students colour the boxes and write the sum underneath.
Related
Questions
Why split by place value?
23 × 14 is hard to do in one step, but 20 × 10, 20 × 4, 3 × 10 and 3 × 4 are facts. The area model adds them back together.
How large can the numbers be?
Whole numbers up to 99, so the rectangle never has more than four boxes.
Is anything saved or sent?
No. The numbers you type stay in this browser tab.
Nothing you do here is sent to us. Names, lists and settings stay in this browser. No sign-in, no ads. What each tool stores