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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 585 · 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 74 × 61? (a) 42000 (b) 420 (c) 4200
  2. 2.Best estimate of 51 × 68? (a) 3500 (b) 35000 (c) 350
  3. 3.Best estimate of 87 × 21? (a) 180 (b) 18000 (c) 1800
  4. 4.Best estimate of 664 + 777? (a) 1300 (b) 1700 (c) 1500
  5. 5.Best estimate of 98 × 33? (a) 3000 (b) 300 (c) 30000
  6. 6.Best estimate of 14 × 16? (a) 200 (b) 20 (c) 2000
  7. 7.Best estimate of 23 × 20? (a) 400 (b) 4000 (c) 40
  8. 8.Best estimate of 664 + 251? (a) 800 (b) 1200 (c) 1000
  9. 9.Best estimate of 12 × 41? (a) 400 (b) 40 (c) 4000
  10. 10.Best estimate of 176 + 415? (a) 600 (b) 800 (c) 400
  11. 11.Best estimate of 66 × 62? (a) 42000 (b) 420 (c) 4200
  12. 12.Best estimate of 203 + 611? (a) 1000 (b) 800 (c) 600
  13. 13.Best estimate of 283 + 812? (a) 900 (b) 1300 (c) 1100
  14. 14.Best estimate of 222 + 438? (a) 800 (b) 400 (c) 600
  15. 15.Best estimate of 24 × 47? (a) 10000 (b) 100 (c) 1000
  16. 16.Best estimate of 296 + 416? (a) 900 (b) 500 (c) 700
  17. 17.Best estimate of 732 + 477? (a) 1000 (b) 1400 (c) 1200
  18. 18.Best estimate of 683 + 685? (a) 1600 (b) 1200 (c) 1400
  19. 19.Best estimate of 26 × 96? (a) 30000 (b) 3000 (c) 300
  20. 20.Best estimate of 80 × 40? (a) 3200 (b) 320 (c) 32000
  21. 21.Best estimate of 68 × 51? (a) 3500 (b) 350 (c) 35000
  22. 22.Best estimate of 77 × 83? (a) 64000 (b) 640 (c) 6400
  23. 23.Best estimate of 123 + 780? (a) 1100 (b) 900 (c) 700
  24. 24.Best estimate of 88 × 87? (a) 8100 (b) 810 (c) 81000
  25. 25.Best estimate of 461 + 575? (a) 1100 (b) 900 (c) 1300
  26. 26.Best estimate of 20 × 64? (a) 1200 (b) 120 (c) 12000
  27. 27.Best estimate of 324 + 617? (a) 1100 (b) 900 (c) 700
  28. 28.Best estimate of 86 × 67? (a) 63000 (b) 6300 (c) 630
  29. 29.Best estimate of 88 × 91? (a) 81000 (b) 8100 (c) 810
  30. 30.Best estimate of 138 + 149? (a) 400 (b) 200 (c) 0
  31. 31.Best estimate of 96 × 92? (a) 90000 (b) 900 (c) 9000
  32. 32.Best estimate of 19 × 80? (a) 1600 (b) 16000 (c) 160
  33. 33.Best estimate of 528 + 808? (a) 1500 (b) 1100 (c) 1300
  34. 34.Best estimate of 867 + 482? (a) 1200 (b) 1400 (c) 1600
  35. 35.Best estimate of 76 × 68? (a) 56000 (b) 5600 (c) 560
  36. 36.Best estimate of 782 + 315? (a) 1100 (b) 900 (c) 1300
  37. 37.Best estimate of 617 + 226? (a) 1000 (b) 800 (c) 600
  38. 38.Best estimate of 563 + 589? (a) 1000 (b) 1400 (c) 1200
  39. 39.Best estimate of 37 × 40? (a) 160 (b) 16000 (c) 1600
  40. 40.Best estimate of 44 × 66? (a) 2800 (b) 28000 (c) 280

Answer key

  1. 4200
  2. 3500
  3. 1800
  4. 1500
  5. 3000
  6. 200
  7. 400
  8. 1000
  9. 400
  10. 600
  11. 4200
  12. 800
  13. 1100
  14. 600
  15. 1000
  16. 700
  17. 1200
  18. 1400
  19. 3000
  20. 3200
  21. 3500
  22. 6400
  23. 900
  24. 8100
  25. 1100
  26. 1200
  27. 900
  28. 6300
  29. 8100
  30. 200
  31. 9000
  32. 1600
  33. 1300
  34. 1400
  35. 5600
  36. 1100
  37. 800
  38. 1200
  39. 1600
  40. 2800

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