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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 474 · 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 × 86? (a) 720 (b) 72000 (c) 7200
  2. 2.Best estimate of 48 × 67? (a) 35000 (b) 350 (c) 3500
  3. 3.Best estimate of 769 + 794? (a) 1600 (b) 1800 (c) 1400
  4. 4.Best estimate of 24 × 64? (a) 120 (b) 1200 (c) 12000
  5. 5.Best estimate of 608 + 582? (a) 1000 (b) 1200 (c) 1400
  6. 6.Best estimate of 16 × 34? (a) 600 (b) 6000 (c) 60
  7. 7.Best estimate of 69 × 22? (a) 140 (b) 1400 (c) 14000
  8. 8.Best estimate of 57 × 29? (a) 1800 (b) 180 (c) 18000
  9. 9.Best estimate of 67 × 66? (a) 4900 (b) 490 (c) 49000
  10. 10.Best estimate of 98 × 41? (a) 4000 (b) 400 (c) 40000
  11. 11.Best estimate of 249 + 565? (a) 800 (b) 600 (c) 1000
  12. 12.Best estimate of 49 × 40? (a) 200 (b) 2000 (c) 20000
  13. 13.Best estimate of 236 + 390? (a) 800 (b) 600 (c) 400
  14. 14.Best estimate of 637 + 125? (a) 900 (b) 500 (c) 700
  15. 15.Best estimate of 54 × 56? (a) 300 (b) 30000 (c) 3000
  16. 16.Best estimate of 280 + 769? (a) 1100 (b) 1300 (c) 900
  17. 17.Best estimate of 481 + 866? (a) 1600 (b) 1200 (c) 1400
  18. 18.Best estimate of 535 + 372? (a) 700 (b) 1100 (c) 900
  19. 19.Best estimate of 20 × 54? (a) 100 (b) 1000 (c) 10000
  20. 20.Best estimate of 622 + 465? (a) 1100 (b) 900 (c) 1300
  21. 21.Best estimate of 180 + 838? (a) 1000 (b) 800 (c) 1200
  22. 22.Best estimate of 16 × 69? (a) 140 (b) 1400 (c) 14000
  23. 23.Best estimate of 66 × 77? (a) 5600 (b) 56000 (c) 560
  24. 24.Best estimate of 38 × 39? (a) 1600 (b) 16000 (c) 160
  25. 25.Best estimate of 764 + 508? (a) 1500 (b) 1100 (c) 1300
  26. 26.Best estimate of 77 × 91? (a) 7200 (b) 720 (c) 72000
  27. 27.Best estimate of 41 × 63? (a) 2400 (b) 240 (c) 24000
  28. 28.Best estimate of 760 + 509? (a) 1300 (b) 1100 (c) 1500
  29. 29.Best estimate of 16 × 14? (a) 200 (b) 20 (c) 2000
  30. 30.Best estimate of 590 + 308? (a) 1100 (b) 900 (c) 700
  31. 31.Best estimate of 79 × 91? (a) 72000 (b) 720 (c) 7200
  32. 32.Best estimate of 687 + 689? (a) 1400 (b) 1600 (c) 1200
  33. 33.Best estimate of 76 × 48? (a) 40000 (b) 4000 (c) 400
  34. 34.Best estimate of 96 × 21? (a) 2000 (b) 200 (c) 20000
  35. 35.Best estimate of 80 × 48? (a) 4000 (b) 400 (c) 40000
  36. 36.Best estimate of 39 × 44? (a) 1600 (b) 16000 (c) 160
  37. 37.Best estimate of 307 + 435? (a) 900 (b) 500 (c) 700
  38. 38.Best estimate of 333 + 259? (a) 400 (b) 600 (c) 800
  39. 39.Best estimate of 315 + 420? (a) 700 (b) 500 (c) 900
  40. 40.Best estimate of 373 + 266? (a) 900 (b) 700 (c) 500

Answer key

  1. 7200
  2. 3500
  3. 1600
  4. 1200
  5. 1200
  6. 600
  7. 1400
  8. 1800
  9. 4900
  10. 4000
  11. 800
  12. 2000
  13. 600
  14. 700
  15. 3000
  16. 1100
  17. 1400
  18. 900
  19. 1000
  20. 1100
  21. 1000
  22. 1400
  23. 5600
  24. 1600
  25. 1300
  26. 7200
  27. 2400
  28. 1300
  29. 200
  30. 900
  31. 7200
  32. 1400
  33. 4000
  34. 2000
  35. 4000
  36. 1600
  37. 700
  38. 600
  39. 700
  40. 700

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