โ๏ธ Multiplication ๐ Grade 3-4 โฑ 7 min
Multi-Digit Multiplication: How to Teach Step by Step
The problem 23ร14 looks scary before the distributive property. After it โ just two multiplications and one addition.
The distributive property โ the key
23ร14 = 23ร10 + 23ร4. A big problem splits into two small ones by breaking the second factor by place value. The idea opens up through an area rectangle.
๐ก Prerequisites: fluent times tables, multiplying by 10, adding three-digit numbers. Gaps here turn the distributive property into chaos.
The rectangle model
A 23-by-14 rectangle splits with a vertical line into two: 23ร10 and 23ร4. Their areas add up: 230+92=322. The child sees both partial products before writing a column.
The column algorithm
Three steps
Example 23ร14:
Step 1: multiply by 4 โ 23ร4=92
Step 2: multiply by 10 โ 23ร10=230 (shift row left)
Step 3: add โ 92+230=322
Practice chain:
21ร12=252 ยท 13ร21=273
32ร14=448 ยท 25ร13=325
45ร23=1035 ยท 34ร31=1054
21ร12=252 ยท 13ร21=273
32ร14=448 ยท 25ร13=325
45ร23=1035 ยท 34ร31=1054
Common mistakes
- Forgotten row shift โ the rectangle reminds: the second product is tens
- Addition errors on large numbers โ use column addition
- Multiplying by 1 instead of 10 โ say it aloud before writing
โ๏ธ The times table is the foundation!
Every algorithm step rests on the times table. Our Pro game drives it to automatic.
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