Double Digit Multiplication Answer Key
Teacher Answer Key
Solutions
Double Digit Multiplication • Standard Algorithm & Partial Products
Part 1 • Solutions 1–5
Standard Algorithm & Area Models • Regrouping & Partial Product Breakdowns
Max Score: 10 Points
Problem 01 34 × 26 = 884
²
34
× 26
204
884
Step 1: 34 × 6 = 204
Step 2: 34 × 20 = 680 (0 placed)
Step 3: 204 + 680 = 884
Estimate: 30 × 30 = 900 Answer: 884
Problem 02 58 × 43 = 2,494
³ ²
58
× 43
174
2,494
Step 1: 58 × 3 = 174
Step 2: 58 × 40 = 2,320
Step 3: 174 + 2,320 = 2,494
Estimate: 60 × 40 = 2,400 Answer: 2,494
Problem 03 72 × 35 = 2,520
¹
72
× 35
360
2,520
Step 1: 72 × 5 = 360
Step 2: 72 × 30 = 2,160
Step 3: 360 + 2,160 = 2,520
Estimate: 70 × 35 = 2,450 Answer: 2,520
Problem 04 49 × 67 = 3,283
⁵ ⁶
49
× 67
343
3,283
Step 1: 49 × 7 = 343
Step 2: 49 × 60 = 2,940
Step 3: 343 + 2,940 = 3,283
Estimate: 50 × 70 = 3,500 Answer: 3,283
Problem 05 83 × 54 = 4,482
¹ ¹
83
× 54
332
4,482
Step 1: 83 × 4 = 332
Step 2: 83 × 50 = 4,150
Step 3: 332 + 4,150 = 4,482
Estimate: 80 × 50 = 4,000 Answer: 4,482
Grading & Diagnostics
Scoring Rubric
Points Per Problem (1 pt each):
- • 0.5 pt: Correct partial products with placeholder 0.
- • 0.5 pt: Accurate column addition and final sum.
Common Student Errors to Check:
- • Missing Placeholder 0: Causes answers off by an order of magnitude.
- • Carry Over Misplacement: Adding carry before multiplying next place value.
Page 2: Solutions 6–10 & Star Challenge →
2
Teacher Answer Key | Solutions 6–10 & Star Challenge
Full Work & Partial Products
Problem 06 64 × 38 = 2,432
¹ ³
64
× 38
512
2,432
Step 1: 64 × 8 = 512
Step 2: 64 × 30 = 1,920
Step 3: 512 + 1,920 = 2,432
Estimate: 60 × 40 = 2,400 Answer: 2,432
Problem 07 91 × 47 = 4,277
-
91
× 47
637
4,277
Step 1: 91 × 7 = 637
Step 2: 91 × 40 = 3,640
Step 3: 637 + 3,640 = 4,277
Estimate: 90 × 50 = 4,500 Answer: 4,277
Problem 08 53 × 76 = 4,028
² ¹
53
× 76
318
4,028
Step 1: 53 × 6 = 318
Step 2: 53 × 70 = 3,710
Step 3: 318 + 3,710 = 4,028
Estimate: 50 × 80 = 4,000 Answer: 4,028
Problem 09 28 × 89 = 2,492
⁶ ⁷
28
× 89
252
2,492
Step 1: 28 × 9 = 252
Step 2: 28 × 80 = 2,240
Step 3: 252 + 2,240 = 2,492
Estimate: 30 × 90 = 2,700 Answer: 2,492
Problem 10 75 × 62 = 4,650
³ ¹
75
× 62
150
4,650
Step 1: 75 × 2 = 150
Step 2: 75 × 60 = 4,500
Step 3: 150 + 4,500 = 4,650
Estimate: 80 × 60 = 4,800 Answer: 4,650
Star Challenge Solution
= 1,728
Equation: 48 boxes × 36 books/box
² ⁴
48
× 36
288
1,728
• 48 × 6 = 288
• 48 × 30 = 1,440
• 288 + 1,440 = 1,728
✓ Unit: books
Estimate: 50 × 35 = 1,750 Answer: 1,728 books