Multi-Digit Multiplication — Answer Key
Part A: Multiple Choice
Circle the best answer for each question.
1. A factory produces 2,364 widgets per day. How many widgets does it produce in 8 days?
A) 18,112
B) 18,812
C) 18,912
D) 19,112
2,364×8: 4×8=32 (write 2, carry 3); 6×8+3=51 (write 1, carry 5); 3×8+5=29 (write 9, carry 2); 2×8+2=18. Product = 18,912.
2. Which expression has the greatest product?
A) 55 × 38
B) 49 × 42
C) 61 × 34
D) 72 × 29
55×38=2,090; 49×42=2,058; 61×34=2,074; 72×29=2,088. Greatest product: 55×38=2,090.
3. Marcus reads 47 pages each day for 23 days. How many pages does he read?
A) 981
B) 1,061
C) 1,081
D) 1,181
47×23: 47×3=141; 47×20=940; 141+940=1,081.
4. Estimating 684 × 7 by rounding 684 to 700 gives an estimate of:
A) 4,200
B) 4,700
C) 4,900
D) 5,600
700×7=4,900. (Actual: 684×7=4,788.)
Part B: Fill in the Blank
Write the correct answer on each line.
1. 3,478 × 6 = 20,868
8×6=48 (write 8, carry 4); 7×6+4=46 (write 6, carry 4); 4×6+4=28 (write 8, carry 2); 3×6+2=20. Product = 20,868.
2. 74 × 68 = 5,032
74×8=592; 74×60=4,440; 592+4,440=5,032.
3. A store sells 1,245 bottles of water each week. In 9 weeks it sells 11,205 bottles.
1,245×9: 5×9=45 (write 5, carry 4); 4×9+4=40 (write 0, carry 4); 2×9+4=22 (write 2, carry 2); 1×9+2=11. Product = 11,205.
4. 93 × 85 = 7,905
93×5=465; 93×80=7,440; 465+7,440=7,905.
5. To check 256 × 3 = 768, divide 768 by 3 to get 256.
Division is the inverse of multiplication. 768 ÷ 3 = 256 confirms the product is correct.