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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 145 · 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 82 × 28? (a) 240 (b) 2400 (c) 24000
  2. 2.Best estimate of 695 + 718? (a) 1200 (b) 1600 (c) 1400
  3. 3.Best estimate of 649 + 167? (a) 1000 (b) 800 (c) 600
  4. 4.Best estimate of 824 + 512? (a) 1100 (b) 1300 (c) 1500
  5. 5.Best estimate of 166 + 348? (a) 700 (b) 500 (c) 300
  6. 6.Best estimate of 494 + 618? (a) 1100 (b) 900 (c) 1300
  7. 7.Best estimate of 19 × 56? (a) 1200 (b) 12000 (c) 120
  8. 8.Best estimate of 98 × 83? (a) 800 (b) 8000 (c) 80000
  9. 9.Best estimate of 48 × 37? (a) 20000 (b) 2000 (c) 200
  10. 10.Best estimate of 442 + 818? (a) 1200 (b) 1000 (c) 1400
  11. 11.Best estimate of 498 + 520? (a) 1200 (b) 800 (c) 1000
  12. 12.Best estimate of 48 × 44? (a) 20000 (b) 200 (c) 2000
  13. 13.Best estimate of 622 + 318? (a) 900 (b) 1100 (c) 700
  14. 14.Best estimate of 491 + 370? (a) 1100 (b) 900 (c) 700
  15. 15.Best estimate of 59 × 59? (a) 3600 (b) 36000 (c) 360
  16. 16.Best estimate of 732 + 272? (a) 1000 (b) 1200 (c) 800
  17. 17.Best estimate of 266 + 639? (a) 700 (b) 1100 (c) 900
  18. 18.Best estimate of 69 × 64? (a) 42000 (b) 420 (c) 4200
  19. 19.Best estimate of 89 × 16? (a) 180 (b) 1800 (c) 18000
  20. 20.Best estimate of 81 × 18? (a) 160 (b) 1600 (c) 16000
  21. 21.Best estimate of 28 × 96? (a) 30000 (b) 300 (c) 3000
  22. 22.Best estimate of 609 + 646? (a) 1400 (b) 1200 (c) 1000
  23. 23.Best estimate of 57 × 13? (a) 600 (b) 6000 (c) 60
  24. 24.Best estimate of 62 × 79? (a) 4800 (b) 48000 (c) 480
  25. 25.Best estimate of 89 × 47? (a) 450 (b) 4500 (c) 45000
  26. 26.Best estimate of 66 × 56? (a) 42000 (b) 4200 (c) 420
  27. 27.Best estimate of 20 × 62? (a) 12000 (b) 120 (c) 1200
  28. 28.Best estimate of 31 × 61? (a) 1800 (b) 18000 (c) 180
  29. 29.Best estimate of 173 + 255? (a) 700 (b) 500 (c) 300
  30. 30.Best estimate of 22 × 46? (a) 100 (b) 1000 (c) 10000
  31. 31.Best estimate of 80 × 16? (a) 16000 (b) 160 (c) 1600
  32. 32.Best estimate of 14 × 66? (a) 700 (b) 7000 (c) 70
  33. 33.Best estimate of 56 × 86? (a) 54000 (b) 5400 (c) 540
  34. 34.Best estimate of 590 + 298? (a) 1100 (b) 700 (c) 900
  35. 35.Best estimate of 17 × 67? (a) 1400 (b) 14000 (c) 140
  36. 36.Best estimate of 817 + 172? (a) 1200 (b) 1000 (c) 800
  37. 37.Best estimate of 86 × 81? (a) 7200 (b) 720 (c) 72000
  38. 38.Best estimate of 58 × 34? (a) 1800 (b) 18000 (c) 180
  39. 39.Best estimate of 292 + 671? (a) 1000 (b) 1200 (c) 800
  40. 40.Best estimate of 29 × 41? (a) 1200 (b) 12000 (c) 120

Answer key

  1. 2400
  2. 1400
  3. 800
  4. 1300
  5. 500
  6. 1100
  7. 1200
  8. 8000
  9. 2000
  10. 1200
  11. 1000
  12. 2000
  13. 900
  14. 900
  15. 3600
  16. 1000
  17. 900
  18. 4200
  19. 1800
  20. 1600
  21. 3000
  22. 1200
  23. 600
  24. 4800
  25. 4500
  26. 4200
  27. 1200
  28. 1800
  29. 500
  30. 1000
  31. 1600
  32. 700
  33. 5400
  34. 900
  35. 1400
  36. 1000
  37. 7200
  38. 1800
  39. 1000
  40. 1200

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