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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 630 · 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 585 + 616? (a) 1000 (b) 1400 (c) 1200
  2. 2.Best estimate of 43 × 90? (a) 360 (b) 36000 (c) 3600
  3. 3.Best estimate of 20 × 20? (a) 400 (b) 40 (c) 4000
  4. 4.Best estimate of 39 × 52? (a) 20000 (b) 2000 (c) 200
  5. 5.Best estimate of 63 × 12? (a) 6000 (b) 600 (c) 60
  6. 6.Best estimate of 311 + 639? (a) 900 (b) 1100 (c) 700
  7. 7.Best estimate of 151 + 635? (a) 1000 (b) 800 (c) 600
  8. 8.Best estimate of 49 × 14? (a) 50 (b) 500 (c) 5000
  9. 9.Best estimate of 58 × 17? (a) 12000 (b) 120 (c) 1200
  10. 10.Best estimate of 86 × 28? (a) 27000 (b) 270 (c) 2700
  11. 11.Best estimate of 77 × 31? (a) 2400 (b) 240 (c) 24000
  12. 12.Best estimate of 248 + 496? (a) 500 (b) 700 (c) 900
  13. 13.Best estimate of 66 × 18? (a) 14000 (b) 140 (c) 1400
  14. 14.Best estimate of 209 + 583? (a) 800 (b) 1000 (c) 600
  15. 15.Best estimate of 322 + 273? (a) 800 (b) 400 (c) 600
  16. 16.Best estimate of 16 × 67? (a) 1400 (b) 140 (c) 14000
  17. 17.Best estimate of 96 × 57? (a) 6000 (b) 600 (c) 60000
  18. 18.Best estimate of 592 + 381? (a) 1000 (b) 1200 (c) 800
  19. 19.Best estimate of 93 × 86? (a) 81000 (b) 810 (c) 8100
  20. 20.Best estimate of 170 + 392? (a) 600 (b) 800 (c) 400
  21. 21.Best estimate of 141 + 716? (a) 600 (b) 1000 (c) 800
  22. 22.Best estimate of 574 + 586? (a) 1200 (b) 1400 (c) 1000
  23. 23.Best estimate of 291 + 298? (a) 600 (b) 400 (c) 800
  24. 24.Best estimate of 228 + 582? (a) 1000 (b) 800 (c) 600
  25. 25.Best estimate of 246 + 483? (a) 700 (b) 500 (c) 900
  26. 26.Best estimate of 39 × 39? (a) 1600 (b) 16000 (c) 160
  27. 27.Best estimate of 436 + 683? (a) 1300 (b) 900 (c) 1100
  28. 28.Best estimate of 16 × 50? (a) 1000 (b) 100 (c) 10000
  29. 29.Best estimate of 829 + 477? (a) 1300 (b) 1500 (c) 1100
  30. 30.Best estimate of 33 × 14? (a) 30 (b) 300 (c) 3000
  31. 31.Best estimate of 56 × 31? (a) 18000 (b) 180 (c) 1800
  32. 32.Best estimate of 400 + 682? (a) 900 (b) 1100 (c) 1300
  33. 33.Best estimate of 865 + 447? (a) 1300 (b) 1100 (c) 1500
  34. 34.Best estimate of 837 + 760? (a) 1800 (b) 1400 (c) 1600
  35. 35.Best estimate of 570 + 152? (a) 600 (b) 800 (c) 1000
  36. 36.Best estimate of 878 + 233? (a) 1300 (b) 1100 (c) 900
  37. 37.Best estimate of 166 + 573? (a) 600 (b) 800 (c) 1000
  38. 38.Best estimate of 524 + 539? (a) 1200 (b) 800 (c) 1000
  39. 39.Best estimate of 26 × 16? (a) 600 (b) 60 (c) 6000
  40. 40.Best estimate of 751 + 554? (a) 1400 (b) 1200 (c) 1600

Answer key

  1. 1200
  2. 3600
  3. 400
  4. 2000
  5. 600
  6. 900
  7. 800
  8. 500
  9. 1200
  10. 2700
  11. 2400
  12. 700
  13. 1400
  14. 800
  15. 600
  16. 1400
  17. 6000
  18. 1000
  19. 8100
  20. 600
  21. 800
  22. 1200
  23. 600
  24. 800
  25. 700
  26. 1600
  27. 1100
  28. 1000
  29. 1300
  30. 300
  31. 1800
  32. 1100
  33. 1300
  34. 1600
  35. 800
  36. 1100
  37. 800
  38. 1000
  39. 600
  40. 1400

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