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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 735 · 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 66 × 26? (a) 2100 (b) 210 (c) 21000
  2. 2.Best estimate of 159 + 268? (a) 500 (b) 700 (c) 300
  3. 3.Best estimate of 434 + 365? (a) 600 (b) 1000 (c) 800
  4. 4.Best estimate of 93 × 22? (a) 180 (b) 1800 (c) 18000
  5. 5.Best estimate of 582 + 621? (a) 1200 (b) 1000 (c) 1400
  6. 6.Best estimate of 351 + 409? (a) 800 (b) 1000 (c) 600
  7. 7.Best estimate of 148 + 802? (a) 900 (b) 1100 (c) 700
  8. 8.Best estimate of 846 + 659? (a) 1500 (b) 1300 (c) 1700
  9. 9.Best estimate of 436 + 394? (a) 800 (b) 600 (c) 1000
  10. 10.Best estimate of 88 × 66? (a) 6300 (b) 63000 (c) 630
  11. 11.Best estimate of 54 × 18? (a) 1000 (b) 100 (c) 10000
  12. 12.Best estimate of 50 × 43? (a) 2000 (b) 200 (c) 20000
  13. 13.Best estimate of 596 + 573? (a) 1400 (b) 1000 (c) 1200
  14. 14.Best estimate of 390 + 257? (a) 700 (b) 900 (c) 500
  15. 15.Best estimate of 217 + 323? (a) 500 (b) 300 (c) 700
  16. 16.Best estimate of 58 × 18? (a) 1200 (b) 120 (c) 12000
  17. 17.Best estimate of 91 × 13? (a) 900 (b) 9000 (c) 90
  18. 18.Best estimate of 16 × 20? (a) 40 (b) 4000 (c) 400
  19. 19.Best estimate of 52 × 46? (a) 2500 (b) 25000 (c) 250
  20. 20.Best estimate of 687 + 141? (a) 800 (b) 600 (c) 1000
  21. 21.Best estimate of 36 × 36? (a) 1600 (b) 16000 (c) 160
  22. 22.Best estimate of 178 + 151? (a) 400 (b) 200 (c) 600
  23. 23.Best estimate of 641 + 292? (a) 1100 (b) 900 (c) 700
  24. 24.Best estimate of 351 + 286? (a) 500 (b) 700 (c) 900
  25. 25.Best estimate of 762 + 551? (a) 1600 (b) 1400 (c) 1200
  26. 26.Best estimate of 376 + 468? (a) 700 (b) 1100 (c) 900
  27. 27.Best estimate of 73 × 29? (a) 2100 (b) 210 (c) 21000
  28. 28.Best estimate of 527 + 526? (a) 1000 (b) 1200 (c) 800
  29. 29.Best estimate of 24 × 16? (a) 400 (b) 4000 (c) 40
  30. 30.Best estimate of 29 × 88? (a) 270 (b) 27000 (c) 2700
  31. 31.Best estimate of 184 + 322? (a) 700 (b) 500 (c) 300
  32. 32.Best estimate of 21 × 30? (a) 6000 (b) 600 (c) 60
  33. 33.Best estimate of 71 × 19? (a) 14000 (b) 1400 (c) 140
  34. 34.Best estimate of 24 × 84? (a) 1600 (b) 160 (c) 16000
  35. 35.Best estimate of 62 × 74? (a) 420 (b) 4200 (c) 42000
  36. 36.Best estimate of 256 + 651? (a) 1000 (b) 800 (c) 1200
  37. 37.Best estimate of 43 × 37? (a) 1600 (b) 16000 (c) 160
  38. 38.Best estimate of 97 × 44? (a) 40000 (b) 400 (c) 4000
  39. 39.Best estimate of 24 × 31? (a) 6000 (b) 600 (c) 60
  40. 40.Best estimate of 46 × 56? (a) 300 (b) 30000 (c) 3000

Answer key

  1. 2100
  2. 500
  3. 800
  4. 1800
  5. 1200
  6. 800
  7. 900
  8. 1500
  9. 800
  10. 6300
  11. 1000
  12. 2000
  13. 1200
  14. 700
  15. 500
  16. 1200
  17. 900
  18. 400
  19. 2500
  20. 800
  21. 1600
  22. 400
  23. 900
  24. 700
  25. 1400
  26. 900
  27. 2100
  28. 1000
  29. 400
  30. 2700
  31. 500
  32. 600
  33. 1400
  34. 1600
  35. 4200
  36. 1000
  37. 1600
  38. 4000
  39. 600
  40. 3000

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