Multiplying by a one-digit number worksheet

Part A: Working out and filling in

1. 1. 40, 2, 42

   Split 21 into 20 and 1, multiply each by 2, then add the two products.

   Tens: 20 × 2 = 40; ones: 1 × 2 = 2; 40 + 2 = 42.

2. 2. 360

   Leave the 0 aside and work out 6 × 6; put the 0 back at the end.

   First 6 × 6 = 36, then put the 0 back: 360.

3. 3. 18 × 8 = 144

   18 × 8: split 18 into 10 and 8, 10 × 8 = 80, 8 × 8 = 64, 80 + 64 = 144

4. 4. 35 × 6 = 210

   35 × 6: split 35 into 30 and 5, 30 × 6 = 180, 5 × 6 = 30, 180 + 30 = 210

5. 5. 476 × 9 = 4284

   476 × 9: split 476 into 400 + 70 + 6, 400 × 9 = 3600, 70 × 9 = 630, 6 × 9 = 54, 3600 + 630 = 4230, 4230 + 54 = 4284

6. 6. 393 × 4 = 1572

   393 × 4: split 393 into 300 + 90 + 3, 300 × 4 = 1200, 90 × 4 = 360, 3 × 4 = 12, 1200 + 360 = 1560, 1560 + 12 = 1572

7. 7. 320

   Round 78 to the nearest ten first, then multiply by 4.

   The nearest ten to 78 is 80: 80 × 4 = 320.

8. 8. 36

   Work left to right: 4 × 3 first, then multiply that by 3.

   Left to right: 4 × 3 = 12, 12 × 3 = 36, so the answer is 36.

9. 9. 4 × 53 × 25 = 5300

   4 × 53 × 25: multiply the easy pair first, 25 × 4 = 100, then 53 × 100 = 5300

10. 10. 25 × 4 × 83 = 8300

    25 × 4 × 83: multiply the easy pair first, 25 × 4 = 100, then 83 × 100 = 8300

Part B: Choose, or true or false

1. 11. False

   Estimate first: 23 is about how many tens? About how much is that times 5? Then compare with 1150.

   Estimate: 23 is about 20, and 20 × 5 = 100. Compare 1150 with 100: close is reasonable; a zero too many is not.

2. 12. False

   You can do the last two first. What is 8 × 6? Then compare with 14.

   You can do 8 × 6 = 48 first, so 7 × 8 × 6 = 7 × 48.

Part C: Word problems

Marking: 2 for the working, 1 for the answer, 1 for the sentence.

1. 13. 32 seats

   First find how many seats there are: 3 coaches of 40. Then subtract the people already on.

   40 × 3 = 120 seats, and 120 − 88 = 32.

2. 14. Each crate holds 31 kiwis. A fruit shop gets 9 crates. How many kiwis is that? (Answer: 279 kiwis)

   31 × 9 = 279

3. 15. A pack of printer paper has 948 sheets. An office buys 5 packs and uses 88 sheets. How many sheets are left? (Answer: 4652 sheets)

   948 × 5 = 4740; 948 × 5 − 88 = 4652

4. 16. 560 skips

   Round 77 to the nearest ten first, then multiply by 7 days.

   77 is about 80: 80 × 7 = 560.

5. 17. 135 dollars

   Work out one box first: 9 pens at $3 each. Then multiply by 5 boxes.

   3 × 9 × 5 = 135.

6. 18. A hall's seats are in 10 blocks, each of 4 rows with 25 seats in a row. How many seats does the hall have? (Answer: 1000 seats)

   4 × 25 = 100; 10 × 4 × 25 = 1000