Answer Keys: Multi-digit Multiplication

Grade 4 Mathematics | FAST Success Kit

Teacher/Parent Resource: This page contains all answers. Keep separate from student materials.
Student Concept Worksheet Answers
1. 34 x 26 (Area Model)
30x20=600, 30x6=180, 4x20=80, 4x6=24 = 884
2. 47 x 52
2,444
3. 3,825 x 6
22,950
4. 1,234 x 8
9,872
5. 28 classrooms x 32 desks
896 desks
Practice Worksheet Answers

Part A: 4-digit by 1-digit

1.
14,070
2.
29,526
3.
14,028
4.
34,145
5.
15,568
6.
45,657
7.
25,386
8.
43,110

Part B: 2-digit by 2-digit

9.
918
10.
2,408
11.
2,736
12.
2,790
13.
2,136
14.
3,551
15.
3,648
16.
3,185

Part C: Area Model

17. 25 x 34
600+100+150+20 = 850
18. 46 x 28
800+320+120+48 = 1,288
19. 63 x 45
2400+300+120+15 = 2,835
20. 57 x 32
1500+100+210+14 = 1,824

Part D: Word Problems

21. 24 x 36
864 seats
22. 1,250 x 8
10,000 pencils
23. 45 x 52
2,340 muffins
24. 67 x 84
5,628 corn plants
25. 4,850 x 6
29,100 miles
FAST Practice Quiz Answers
1
B. 24,192
3,456 x 7: (3,000 x 7) + (400 x 7) + (50 x 7) + (6 x 7) = 21,000 + 2,800 + 350 + 42 = 24,192
2
B. 120
The box shows 30 x 4 = 120. (Not 34 or 124 - those confuse the numbers)
3
C. 2,726
47 x 58: (40 x 58) + (7 x 58) = 2,320 + 406 = 2,726. Or use area model: 40x50=2000, 40x8=320, 7x50=350, 7x8=56 = 2,726
4
B. 1,260 books
28 x 45: (28 x 40) + (28 x 5) = 1,120 + 140 = 1,260 books
5
14,235
2,847 x 5: (2,000 x 5) + (800 x 5) + (40 x 5) + (7 x 5) = 10,000 + 4,000 + 200 + 35 = 14,235
6
D. Both B and C are correct
The distributive property works both ways: 43x26 = (40+3)x26 = 40x26 + 3x26. Also: 43x26 = 43x(20+6) = 43x20 + 43x6. Both give the same answer!
7
B. 4,745
65 x 73: (65 x 70) + (65 x 3) = 4,550 + 195 = 4,745
8
C. 8,910 toys
1,485 x 6: (1,000 x 6) + (400 x 6) + (80 x 6) + (5 x 6) = 6,000 + 2,400 + 480 + 30 = 8,910
9
4,018
82 x 49: (82 x 50) - (82 x 1) = 4,100 - 82 = 4,018. Or: (80 x 49) + (2 x 49) = 3,920 + 98 = 4,018
10
C. 4,032 seats
56 x 72: (56 x 70) + (56 x 2) = 3,920 + 112 = 4,032 seats

Scoring Guide

Assessment Total Points Proficient (70%+) Needs Support
Student Concept Worksheet 5 points 4+ correct Review area model method
Practice Worksheet 25 points 18+ correct Focus on place value in multiplication
FAST Practice Quiz 10 points 7+ correct Connect area model to algorithm

Common Errors: Forgetting to add partial products, place value errors when multiplying by tens, regrouping mistakes, not lining up numbers correctly in standard algorithm.

FAST Success Kit | Grade 4 | FL B.E.S.T. Standard: MA.4.NSO.2.1