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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 521 · 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 87 × 27? (a) 270 (b) 27000 (c) 2700
  2. 2.Best estimate of 40 × 93? (a) 36000 (b) 360 (c) 3600
  3. 3.Best estimate of 61 × 36? (a) 240 (b) 2400 (c) 24000
  4. 4.Best estimate of 12 × 78? (a) 8000 (b) 800 (c) 80
  5. 5.Best estimate of 21 × 26? (a) 60 (b) 6000 (c) 600
  6. 6.Best estimate of 751 + 596? (a) 1200 (b) 1600 (c) 1400
  7. 7.Best estimate of 52 × 97? (a) 50000 (b) 5000 (c) 500
  8. 8.Best estimate of 288 + 374? (a) 900 (b) 500 (c) 700
  9. 9.Best estimate of 57 × 84? (a) 480 (b) 4800 (c) 48000
  10. 10.Best estimate of 160 + 679? (a) 900 (b) 700 (c) 1100
  11. 11.Best estimate of 635 + 254? (a) 900 (b) 1100 (c) 700
  12. 12.Best estimate of 79 × 64? (a) 48000 (b) 480 (c) 4800
  13. 13.Best estimate of 76 × 86? (a) 7200 (b) 720 (c) 72000
  14. 14.Best estimate of 246 + 539? (a) 500 (b) 900 (c) 700
  15. 15.Best estimate of 37 × 36? (a) 16000 (b) 1600 (c) 160
  16. 16.Best estimate of 208 + 375? (a) 600 (b) 800 (c) 400
  17. 17.Best estimate of 62 × 61? (a) 36000 (b) 3600 (c) 360
  18. 18.Best estimate of 252 + 564? (a) 700 (b) 1100 (c) 900
  19. 19.Best estimate of 90 × 46? (a) 45000 (b) 450 (c) 4500
  20. 20.Best estimate of 800 + 515? (a) 1100 (b) 1300 (c) 1500
  21. 21.Best estimate of 53 × 39? (a) 200 (b) 2000 (c) 20000
  22. 22.Best estimate of 54 × 23? (a) 10000 (b) 100 (c) 1000
  23. 23.Best estimate of 184 + 126? (a) 300 (b) 100 (c) 500
  24. 24.Best estimate of 366 + 275? (a) 700 (b) 500 (c) 900
  25. 25.Best estimate of 251 + 678? (a) 1200 (b) 1000 (c) 800
  26. 26.Best estimate of 86 × 76? (a) 7200 (b) 72000 (c) 720
  27. 27.Best estimate of 46 × 23? (a) 1000 (b) 10000 (c) 100
  28. 28.Best estimate of 72 × 18? (a) 140 (b) 1400 (c) 14000
  29. 29.Best estimate of 80 × 26? (a) 24000 (b) 240 (c) 2400
  30. 30.Best estimate of 12 × 82? (a) 80 (b) 8000 (c) 800
  31. 31.Best estimate of 439 + 790? (a) 1400 (b) 1200 (c) 1000
  32. 32.Best estimate of 16 × 46? (a) 10000 (b) 100 (c) 1000
  33. 33.Best estimate of 56 × 38? (a) 24000 (b) 240 (c) 2400
  34. 34.Best estimate of 69 × 56? (a) 420 (b) 42000 (c) 4200
  35. 35.Best estimate of 481 + 863? (a) 1600 (b) 1200 (c) 1400
  36. 36.Best estimate of 722 + 295? (a) 800 (b) 1200 (c) 1000
  37. 37.Best estimate of 543 + 649? (a) 1300 (b) 1100 (c) 900
  38. 38.Best estimate of 362 + 160? (a) 400 (b) 600 (c) 800
  39. 39.Best estimate of 74 × 74? (a) 49000 (b) 490 (c) 4900
  40. 40.Best estimate of 168 + 600? (a) 800 (b) 600 (c) 1000

Answer key

  1. 2700
  2. 3600
  3. 2400
  4. 800
  5. 600
  6. 1400
  7. 5000
  8. 700
  9. 4800
  10. 900
  11. 900
  12. 4800
  13. 7200
  14. 700
  15. 1600
  16. 600
  17. 3600
  18. 900
  19. 4500
  20. 1300
  21. 2000
  22. 1000
  23. 300
  24. 700
  25. 1000
  26. 7200
  27. 1000
  28. 1400
  29. 2400
  30. 800
  31. 1200
  32. 1000
  33. 2400
  34. 4200
  35. 1400
  36. 1000
  37. 1100
  38. 600
  39. 4900
  40. 800

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