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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 609 · 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 24 × 87? (a) 1800 (b) 180 (c) 18000
  2. 2.Best estimate of 41 × 92? (a) 360 (b) 36000 (c) 3600
  3. 3.Best estimate of 97 × 30? (a) 30000 (b) 3000 (c) 300
  4. 4.Best estimate of 66 × 57? (a) 42000 (b) 420 (c) 4200
  5. 5.Best estimate of 63 × 46? (a) 300 (b) 30000 (c) 3000
  6. 6.Best estimate of 751 + 197? (a) 800 (b) 1200 (c) 1000
  7. 7.Best estimate of 165 + 759? (a) 800 (b) 1000 (c) 1200
  8. 8.Best estimate of 544 + 787? (a) 1100 (b) 1500 (c) 1300
  9. 9.Best estimate of 381 + 444? (a) 600 (b) 1000 (c) 800
  10. 10.Best estimate of 47 × 31? (a) 1500 (b) 150 (c) 15000
  11. 11.Best estimate of 51 × 31? (a) 15000 (b) 150 (c) 1500
  12. 12.Best estimate of 12 × 30? (a) 3000 (b) 30 (c) 300
  13. 13.Best estimate of 632 + 141? (a) 900 (b) 700 (c) 500
  14. 14.Best estimate of 81 × 32? (a) 24000 (b) 2400 (c) 240
  15. 15.Best estimate of 582 + 716? (a) 1300 (b) 1100 (c) 1500
  16. 16.Best estimate of 631 + 270? (a) 900 (b) 700 (c) 1100
  17. 17.Best estimate of 144 + 171? (a) 300 (b) 100 (c) 500
  18. 18.Best estimate of 52 × 76? (a) 400 (b) 40000 (c) 4000
  19. 19.Best estimate of 648 + 686? (a) 1300 (b) 1100 (c) 1500
  20. 20.Best estimate of 58 × 56? (a) 36000 (b) 360 (c) 3600
  21. 21.Best estimate of 270 + 254? (a) 400 (b) 600 (c) 800
  22. 22.Best estimate of 642 + 304? (a) 900 (b) 1100 (c) 700
  23. 23.Best estimate of 136 + 787? (a) 1100 (b) 900 (c) 700
  24. 24.Best estimate of 368 + 451? (a) 900 (b) 700 (c) 1100
  25. 25.Best estimate of 219 + 202? (a) 400 (b) 200 (c) 600
  26. 26.Best estimate of 705 + 656? (a) 1400 (b) 1600 (c) 1200
  27. 27.Best estimate of 172 + 382? (a) 600 (b) 400 (c) 800
  28. 28.Best estimate of 43 × 27? (a) 1200 (b) 12000 (c) 120
  29. 29.Best estimate of 94 × 66? (a) 6300 (b) 630 (c) 63000
  30. 30.Best estimate of 731 + 669? (a) 1400 (b) 1600 (c) 1200
  31. 31.Best estimate of 66 × 21? (a) 140 (b) 14000 (c) 1400
  32. 32.Best estimate of 151 + 165? (a) 600 (b) 200 (c) 400
  33. 33.Best estimate of 120 + 295? (a) 400 (b) 600 (c) 200
  34. 34.Best estimate of 215 + 794? (a) 1200 (b) 1000 (c) 800
  35. 35.Best estimate of 16 × 51? (a) 1000 (b) 10000 (c) 100
  36. 36.Best estimate of 86 × 34? (a) 270 (b) 27000 (c) 2700
  37. 37.Best estimate of 54 × 32? (a) 1500 (b) 15000 (c) 150
  38. 38.Best estimate of 27 × 38? (a) 1200 (b) 120 (c) 12000
  39. 39.Best estimate of 71 × 42? (a) 280 (b) 2800 (c) 28000
  40. 40.Best estimate of 93 × 36? (a) 36000 (b) 3600 (c) 360

Answer key

  1. 1800
  2. 3600
  3. 3000
  4. 4200
  5. 3000
  6. 1000
  7. 1000
  8. 1300
  9. 800
  10. 1500
  11. 1500
  12. 300
  13. 700
  14. 2400
  15. 1300
  16. 900
  17. 300
  18. 4000
  19. 1300
  20. 3600
  21. 600
  22. 900
  23. 900
  24. 900
  25. 400
  26. 1400
  27. 600
  28. 1200
  29. 6300
  30. 1400
  31. 1400
  32. 400
  33. 400
  34. 1000
  35. 1000
  36. 2700
  37. 1500
  38. 1200
  39. 2800
  40. 3600

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