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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 530 · 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 52 × 21? (a) 100 (b) 10000 (c) 1000
  2. 2.Best estimate of 29 × 31? (a) 9000 (b) 900 (c) 90
  3. 3.Best estimate of 238 + 170? (a) 200 (b) 400 (c) 600
  4. 4.Best estimate of 536 + 780? (a) 1300 (b) 1100 (c) 1500
  5. 5.Best estimate of 522 + 639? (a) 1300 (b) 1100 (c) 900
  6. 6.Best estimate of 30 × 67? (a) 21000 (b) 2100 (c) 210
  7. 7.Best estimate of 284 + 833? (a) 1300 (b) 1100 (c) 900
  8. 8.Best estimate of 282 + 742? (a) 800 (b) 1200 (c) 1000
  9. 9.Best estimate of 28 × 38? (a) 12000 (b) 1200 (c) 120
  10. 10.Best estimate of 225 + 283? (a) 700 (b) 300 (c) 500
  11. 11.Best estimate of 468 + 846? (a) 1100 (b) 1500 (c) 1300
  12. 12.Best estimate of 62 × 24? (a) 1200 (b) 120 (c) 12000
  13. 13.Best estimate of 31 × 59? (a) 1800 (b) 180 (c) 18000
  14. 14.Best estimate of 214 + 499? (a) 900 (b) 700 (c) 500
  15. 15.Best estimate of 16 × 66? (a) 14000 (b) 1400 (c) 140
  16. 16.Best estimate of 92 × 52? (a) 450 (b) 45000 (c) 4500
  17. 17.Best estimate of 829 + 271? (a) 1300 (b) 900 (c) 1100
  18. 18.Best estimate of 32 × 92? (a) 27000 (b) 270 (c) 2700
  19. 19.Best estimate of 416 + 210? (a) 600 (b) 400 (c) 800
  20. 20.Best estimate of 524 + 776? (a) 1500 (b) 1100 (c) 1300
  21. 21.Best estimate of 286 + 790? (a) 1100 (b) 900 (c) 1300
  22. 22.Best estimate of 142 + 719? (a) 800 (b) 1000 (c) 600
  23. 23.Best estimate of 403 + 746? (a) 900 (b) 1300 (c) 1100
  24. 24.Best estimate of 865 + 465? (a) 1200 (b) 1600 (c) 1400
  25. 25.Best estimate of 304 + 283? (a) 800 (b) 600 (c) 400
  26. 26.Best estimate of 786 + 615? (a) 1400 (b) 1600 (c) 1200
  27. 27.Best estimate of 79 × 17? (a) 160 (b) 1600 (c) 16000
  28. 28.Best estimate of 58 × 76? (a) 48000 (b) 480 (c) 4800
  29. 29.Best estimate of 812 + 558? (a) 1400 (b) 1600 (c) 1200
  30. 30.Best estimate of 668 + 444? (a) 1300 (b) 900 (c) 1100
  31. 31.Best estimate of 37 × 93? (a) 3600 (b) 36000 (c) 360
  32. 32.Best estimate of 84 × 16? (a) 1600 (b) 16000 (c) 160
  33. 33.Best estimate of 761 + 317? (a) 900 (b) 1100 (c) 1300
  34. 34.Best estimate of 51 × 93? (a) 450 (b) 45000 (c) 4500
  35. 35.Best estimate of 44 × 14? (a) 400 (b) 40 (c) 4000
  36. 36.Best estimate of 604 + 529? (a) 1100 (b) 900 (c) 1300
  37. 37.Best estimate of 23 × 84? (a) 1600 (b) 16000 (c) 160
  38. 38.Best estimate of 74 × 16? (a) 140 (b) 1400 (c) 14000
  39. 39.Best estimate of 413 + 235? (a) 800 (b) 600 (c) 400
  40. 40.Best estimate of 36 × 38? (a) 16000 (b) 160 (c) 1600

Answer key

  1. 1000
  2. 900
  3. 400
  4. 1300
  5. 1100
  6. 2100
  7. 1100
  8. 1000
  9. 1200
  10. 500
  11. 1300
  12. 1200
  13. 1800
  14. 700
  15. 1400
  16. 4500
  17. 1100
  18. 2700
  19. 600
  20. 1300
  21. 1100
  22. 800
  23. 1100
  24. 1400
  25. 600
  26. 1400
  27. 1600
  28. 4800
  29. 1400
  30. 1100
  31. 3600
  32. 1600
  33. 1100
  34. 4500
  35. 400
  36. 1100
  37. 1600
  38. 1400
  39. 600
  40. 1600

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