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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 186 · 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 26 × 16? (a) 6000 (b) 600 (c) 60
  2. 2.Best estimate of 497 + 386? (a) 900 (b) 700 (c) 1100
  3. 3.Best estimate of 232 + 624? (a) 1000 (b) 800 (c) 600
  4. 4.Best estimate of 31 × 36? (a) 1200 (b) 120 (c) 12000
  5. 5.Best estimate of 440 + 321? (a) 700 (b) 900 (c) 500
  6. 6.Best estimate of 685 + 343? (a) 1200 (b) 1000 (c) 800
  7. 7.Best estimate of 71 × 58? (a) 420 (b) 42000 (c) 4200
  8. 8.Best estimate of 738 + 499? (a) 1400 (b) 1200 (c) 1000
  9. 9.Best estimate of 22 × 84? (a) 16000 (b) 160 (c) 1600
  10. 10.Best estimate of 53 × 86? (a) 45000 (b) 4500 (c) 450
  11. 11.Best estimate of 59 × 26? (a) 180 (b) 1800 (c) 18000
  12. 12.Best estimate of 61 × 36? (a) 2400 (b) 24000 (c) 240
  13. 13.Best estimate of 16 × 19? (a) 400 (b) 40 (c) 4000
  14. 14.Best estimate of 67 × 70? (a) 49000 (b) 4900 (c) 490
  15. 15.Best estimate of 382 + 649? (a) 1200 (b) 800 (c) 1000
  16. 16.Best estimate of 86 × 96? (a) 9000 (b) 90000 (c) 900
  17. 17.Best estimate of 73 × 22? (a) 1400 (b) 14000 (c) 140
  18. 18.Best estimate of 42 × 50? (a) 2000 (b) 20000 (c) 200
  19. 19.Best estimate of 88 × 20? (a) 1800 (b) 18000 (c) 180
  20. 20.Best estimate of 31 × 33? (a) 900 (b) 9000 (c) 90
  21. 21.Best estimate of 164 + 307? (a) 700 (b) 300 (c) 500
  22. 22.Best estimate of 539 + 125? (a) 600 (b) 400 (c) 800
  23. 23.Best estimate of 251 + 170? (a) 500 (b) 700 (c) 300
  24. 24.Best estimate of 612 + 594? (a) 1000 (b) 1200 (c) 1400
  25. 25.Best estimate of 306 + 388? (a) 700 (b) 500 (c) 900
  26. 26.Best estimate of 349 + 367? (a) 500 (b) 700 (c) 900
  27. 27.Best estimate of 662 + 307? (a) 800 (b) 1000 (c) 1200
  28. 28.Best estimate of 37 × 36? (a) 1600 (b) 16000 (c) 160
  29. 29.Best estimate of 730 + 823? (a) 1500 (b) 1300 (c) 1700
  30. 30.Best estimate of 595 + 658? (a) 1500 (b) 1100 (c) 1300
  31. 31.Best estimate of 76 × 18? (a) 1600 (b) 16000 (c) 160
  32. 32.Best estimate of 94 × 17? (a) 1800 (b) 18000 (c) 180
  33. 33.Best estimate of 89 × 81? (a) 7200 (b) 72000 (c) 720
  34. 34.Best estimate of 78 × 56? (a) 48000 (b) 480 (c) 4800
  35. 35.Best estimate of 66 × 81? (a) 56000 (b) 5600 (c) 560
  36. 36.Best estimate of 32 × 17? (a) 6000 (b) 600 (c) 60
  37. 37.Best estimate of 33 × 78? (a) 24000 (b) 2400 (c) 240
  38. 38.Best estimate of 464 + 351? (a) 900 (b) 1100 (c) 700
  39. 39.Best estimate of 301 + 701? (a) 1000 (b) 1200 (c) 800
  40. 40.Best estimate of 12 × 93? (a) 9000 (b) 90 (c) 900

Answer key

  1. 600
  2. 900
  3. 800
  4. 1200
  5. 700
  6. 1000
  7. 4200
  8. 1200
  9. 1600
  10. 4500
  11. 1800
  12. 2400
  13. 400
  14. 4900
  15. 1000
  16. 9000
  17. 1400
  18. 2000
  19. 1800
  20. 900
  21. 500
  22. 600
  23. 500
  24. 1200
  25. 700
  26. 700
  27. 1000
  28. 1600
  29. 1500
  30. 1300
  31. 1600
  32. 1800
  33. 7200
  34. 4800
  35. 5600
  36. 600
  37. 2400
  38. 900
  39. 1000
  40. 900

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