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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 964 · 40 questions
TalentJR

How to do it in your head (Round, then work): Round each number: 2-digit numbers to the nearest ten, 3-digit numbers to the nearest hundred. Do the easy sum with the round numbers. Choose the option closest to your estimate.

NameDateTime takenScore ___ / 40
  1. 1.Best estimate of 67 × 49? (a) 35000 (b) 350 (c) 3500
  2. 2.Best estimate of 46 × 41? (a) 2000 (b) 200 (c) 20000
  3. 3.Best estimate of 209 + 482? (a) 500 (b) 700 (c) 900
  4. 4.Best estimate of 30 × 36? (a) 12000 (b) 120 (c) 1200
  5. 5.Best estimate of 94 × 43? (a) 36000 (b) 360 (c) 3600
  6. 6.Best estimate of 86 × 20? (a) 180 (b) 18000 (c) 1800
  7. 7.Best estimate of 248 + 873? (a) 1300 (b) 900 (c) 1100
  8. 8.Best estimate of 373 + 278? (a) 900 (b) 500 (c) 700
  9. 9.Best estimate of 17 × 70? (a) 14000 (b) 1400 (c) 140
  10. 10.Best estimate of 36 × 60? (a) 24000 (b) 2400 (c) 240
  11. 11.Best estimate of 19 × 32? (a) 600 (b) 6000 (c) 60
  12. 12.Best estimate of 259 + 558? (a) 1100 (b) 700 (c) 900
  13. 13.Best estimate of 71 × 52? (a) 35000 (b) 350 (c) 3500
  14. 14.Best estimate of 183 + 784? (a) 1000 (b) 800 (c) 1200
  15. 15.Best estimate of 73 × 78? (a) 560 (b) 5600 (c) 56000
  16. 16.Best estimate of 571 + 142? (a) 900 (b) 500 (c) 700
  17. 17.Best estimate of 139 + 615? (a) 700 (b) 500 (c) 900
  18. 18.Best estimate of 74 × 54? (a) 350 (b) 3500 (c) 35000
  19. 19.Best estimate of 212 + 413? (a) 400 (b) 600 (c) 800
  20. 20.Best estimate of 144 + 348? (a) 600 (b) 200 (c) 400
  21. 21.Best estimate of 36 × 80? (a) 320 (b) 32000 (c) 3200
  22. 22.Best estimate of 157 + 646? (a) 1000 (b) 800 (c) 600
  23. 23.Best estimate of 367 + 355? (a) 800 (b) 600 (c) 1000
  24. 24.Best estimate of 241 + 762? (a) 1000 (b) 1200 (c) 800
  25. 25.Best estimate of 83 × 93? (a) 720 (b) 72000 (c) 7200
  26. 26.Best estimate of 58 × 72? (a) 42000 (b) 4200 (c) 420
  27. 27.Best estimate of 12 × 81? (a) 8000 (b) 800 (c) 80
  28. 28.Best estimate of 640 + 612? (a) 1200 (b) 1400 (c) 1000
  29. 29.Best estimate of 18 × 28? (a) 60 (b) 6000 (c) 600
  30. 30.Best estimate of 79 × 76? (a) 640 (b) 64000 (c) 6400
  31. 31.Best estimate of 64 × 16? (a) 120 (b) 12000 (c) 1200
  32. 32.Best estimate of 539 + 206? (a) 900 (b) 500 (c) 700
  33. 33.Best estimate of 21 × 61? (a) 12000 (b) 120 (c) 1200
  34. 34.Best estimate of 131 + 253? (a) 600 (b) 400 (c) 200
  35. 35.Best estimate of 98 × 68? (a) 700 (b) 7000 (c) 70000
  36. 36.Best estimate of 181 + 673? (a) 900 (b) 1100 (c) 700
  37. 37.Best estimate of 609 + 267? (a) 700 (b) 900 (c) 1100
  38. 38.Best estimate of 546 + 163? (a) 700 (b) 500 (c) 900
  39. 39.Best estimate of 12 × 69? (a) 700 (b) 7000 (c) 70
  40. 40.Best estimate of 86 × 86? (a) 8100 (b) 810 (c) 81000

Answer key

  1. 3500
  2. 2000
  3. 700
  4. 1200
  5. 3600
  6. 1800
  7. 1100
  8. 700
  9. 1400
  10. 2400
  11. 600
  12. 900
  13. 3500
  14. 1000
  15. 5600
  16. 700
  17. 700
  18. 3500
  19. 600
  20. 400
  21. 3200
  22. 800
  23. 800
  24. 1000
  25. 7200
  26. 4200
  27. 800
  28. 1200
  29. 600
  30. 6400
  31. 1200
  32. 700
  33. 1200
  34. 400
  35. 7000
  36. 900
  37. 900
  38. 700
  39. 700
  40. 8100

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