Let’s solve each multiplication problem using the area model (also called the box method). We break each number into tens and ones, multiply each part, then add them up.
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Problem 1: 78 × 58
Break 78 → 70 + 8
Break 58 → 50 + 8
Now make a 2x2 grid:
Top row: 70 and 8
Left column: 50 and 8
Multiply:
- 70 × 50 = 3500
- 8 × 50 = 400
- 70 × 8 = 560
- 8 × 8 = 64
Add them:
3500 + 400 = 3900
3900 + 560 = 4460
4460 + 64 =
4524
✔ So, 78 × 58 =
4524
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Problem 2: 85 × 12
Break 85 → 80 + 5
Break 12 → 10 + 2
Grid:
Top: 80, 5
Left: 10, 2
Multiply:
- 80 × 10 = 800
- 5 × 10 = 50
- 80 × 2 = 160
- 5 × 2 = 10
Add:
800 + 50 = 850
850 + 160 = 1010
1010 + 10 =
1020
✔ So, 85 × 12 =
1020
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Problem 3: 82 × 53
Break 82 → 80 + 2
Break 53 → 50 + 3
Grid:
Top: 80, 2
Left: 50, 3
Multiply:
- 80 × 50 = 4000
- 2 × 50 = 100
- 80 × 3 = 240
- 2 × 3 = 6
Add:
4000 + 100 = 4100
4100 + 240 = 4340
4340 + 6 =
4346
✔ So, 82 × 53 =
4346
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Problem 4: 35 × 18
Break 35 → 30 + 5
Break 18 → 10 + 8
Grid:
Top: 30, 5
Left: 10, 8
Multiply:
- 30 × 10 = 300
- 5 × 10 = 50
- 30 × 8 = 240
- 5 × 8 = 40
Add:
300 + 50 = 350
350 + 240 = 590
590 + 40 =
630
✔ So, 35 × 18 =
630
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Problem 5: 11 × 28
Break 11 → 10 + 1
Break 28 → 20 + 8
Grid:
Top: 10, 1
Left: 20, 8
Multiply:
- 10 × 20 = 200
- 1 × 20 = 20
- 10 × 8 = 80
- 1 × 8 = 8
Add:
200 + 20 = 220
220 + 80 = 300
300 + 8 =
308
✔ So, 11 × 28 =
308
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Final Answer:
78 × 58 = 4524
85 × 12 = 1020
82 × 53 = 4346
35 × 18 = 630
11 × 28 = 308
Parent Tip: Review the logic above to help your child master the concept of area model multiplication worksheet 5th grade.
