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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 914 · 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 60 × 60? (a) 36000 (b) 360 (c) 3600
  2. 2.Best estimate of 76 × 51? (a) 4000 (b) 40000 (c) 400
  3. 3.Best estimate of 144 + 292? (a) 600 (b) 400 (c) 200
  4. 4.Best estimate of 539 + 572? (a) 1100 (b) 900 (c) 1300
  5. 5.Best estimate of 17 × 92? (a) 18000 (b) 1800 (c) 180
  6. 6.Best estimate of 24 × 36? (a) 80 (b) 800 (c) 8000
  7. 7.Best estimate of 216 + 411? (a) 800 (b) 400 (c) 600
  8. 8.Best estimate of 721 + 233? (a) 900 (b) 1100 (c) 700
  9. 9.Best estimate of 294 + 693? (a) 1000 (b) 800 (c) 1200
  10. 10.Best estimate of 458 + 618? (a) 1100 (b) 900 (c) 1300
  11. 11.Best estimate of 152 + 862? (a) 1300 (b) 1100 (c) 900
  12. 12.Best estimate of 679 + 338? (a) 1000 (b) 1200 (c) 800
  13. 13.Best estimate of 877 + 143? (a) 1000 (b) 800 (c) 1200
  14. 14.Best estimate of 67 × 32? (a) 21000 (b) 2100 (c) 210
  15. 15.Best estimate of 331 + 658? (a) 1000 (b) 800 (c) 1200
  16. 16.Best estimate of 735 + 652? (a) 1600 (b) 1400 (c) 1200
  17. 17.Best estimate of 36 × 92? (a) 360 (b) 36000 (c) 3600
  18. 18.Best estimate of 355 + 531? (a) 1100 (b) 900 (c) 700
  19. 19.Best estimate of 91 × 66? (a) 630 (b) 6300 (c) 63000
  20. 20.Best estimate of 54 × 19? (a) 10000 (b) 1000 (c) 100
  21. 21.Best estimate of 17 × 72? (a) 1400 (b) 14000 (c) 140
  22. 22.Best estimate of 44 × 36? (a) 160 (b) 16000 (c) 1600
  23. 23.Best estimate of 148 + 686? (a) 600 (b) 1000 (c) 800
  24. 24.Best estimate of 47 × 70? (a) 35000 (b) 350 (c) 3500
  25. 25.Best estimate of 61 × 27? (a) 1800 (b) 18000 (c) 180
  26. 26.Best estimate of 266 + 774? (a) 1100 (b) 900 (c) 1300
  27. 27.Best estimate of 628 + 561? (a) 1200 (b) 1400 (c) 1000
  28. 28.Best estimate of 636 + 500? (a) 1100 (b) 900 (c) 1300
  29. 29.Best estimate of 56 × 17? (a) 120 (b) 12000 (c) 1200
  30. 30.Best estimate of 62 × 62? (a) 36000 (b) 360 (c) 3600
  31. 31.Best estimate of 416 + 262? (a) 900 (b) 700 (c) 500
  32. 32.Best estimate of 53 × 53? (a) 250 (b) 25000 (c) 2500
  33. 33.Best estimate of 73 × 58? (a) 42000 (b) 4200 (c) 420
  34. 34.Best estimate of 76 × 19? (a) 16000 (b) 160 (c) 1600
  35. 35.Best estimate of 24 × 34? (a) 600 (b) 60 (c) 6000
  36. 36.Best estimate of 822 + 283? (a) 1300 (b) 1100 (c) 900
  37. 37.Best estimate of 33 × 23? (a) 600 (b) 6000 (c) 60
  38. 38.Best estimate of 20 × 80? (a) 1600 (b) 16000 (c) 160
  39. 39.Best estimate of 146 + 124? (a) 0 (b) 200 (c) 400
  40. 40.Best estimate of 31 × 20? (a) 60 (b) 6000 (c) 600

Answer key

  1. 3600
  2. 4000
  3. 400
  4. 1100
  5. 1800
  6. 800
  7. 600
  8. 900
  9. 1000
  10. 1100
  11. 1100
  12. 1000
  13. 1000
  14. 2100
  15. 1000
  16. 1400
  17. 3600
  18. 900
  19. 6300
  20. 1000
  21. 1400
  22. 1600
  23. 800
  24. 3500
  25. 1800
  26. 1100
  27. 1200
  28. 1100
  29. 1200
  30. 3600
  31. 700
  32. 2500
  33. 4200
  34. 1600
  35. 600
  36. 1100
  37. 600
  38. 1600
  39. 200
  40. 600

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