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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 760 · 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 79 × 51? (a) 4000 (b) 400 (c) 40000
  2. 2.Best estimate of 87 × 92? (a) 81000 (b) 810 (c) 8100
  3. 3.Best estimate of 32 × 93? (a) 270 (b) 27000 (c) 2700
  4. 4.Best estimate of 43 × 32? (a) 12000 (b) 1200 (c) 120
  5. 5.Best estimate of 418 + 800? (a) 1000 (b) 1200 (c) 1400
  6. 6.Best estimate of 765 + 571? (a) 1600 (b) 1400 (c) 1200
  7. 7.Best estimate of 64 × 78? (a) 4800 (b) 48000 (c) 480
  8. 8.Best estimate of 421 + 204? (a) 600 (b) 400 (c) 800
  9. 9.Best estimate of 194 + 651? (a) 700 (b) 1100 (c) 900
  10. 10.Best estimate of 22 × 50? (a) 100 (b) 10000 (c) 1000
  11. 11.Best estimate of 879 + 602? (a) 1300 (b) 1500 (c) 1700
  12. 12.Best estimate of 507 + 315? (a) 1000 (b) 600 (c) 800
  13. 13.Best estimate of 545 + 703? (a) 1200 (b) 1000 (c) 1400
  14. 14.Best estimate of 376 + 569? (a) 1200 (b) 800 (c) 1000
  15. 15.Best estimate of 98 × 16? (a) 200 (b) 2000 (c) 20000
  16. 16.Best estimate of 78 × 98? (a) 80000 (b) 800 (c) 8000
  17. 17.Best estimate of 616 + 808? (a) 1600 (b) 1400 (c) 1200
  18. 18.Best estimate of 20 × 31? (a) 600 (b) 60 (c) 6000
  19. 19.Best estimate of 50 × 73? (a) 350 (b) 35000 (c) 3500
  20. 20.Best estimate of 785 + 773? (a) 1400 (b) 1800 (c) 1600
  21. 21.Best estimate of 622 + 835? (a) 1600 (b) 1200 (c) 1400
  22. 22.Best estimate of 46 × 58? (a) 3000 (b) 30000 (c) 300
  23. 23.Best estimate of 565 + 466? (a) 1100 (b) 1300 (c) 900
  24. 24.Best estimate of 749 + 827? (a) 1700 (b) 1500 (c) 1300
  25. 25.Best estimate of 28 × 19? (a) 6000 (b) 60 (c) 600
  26. 26.Best estimate of 848 + 785? (a) 1600 (b) 1400 (c) 1800
  27. 27.Best estimate of 50 × 66? (a) 3500 (b) 350 (c) 35000
  28. 28.Best estimate of 631 + 707? (a) 1500 (b) 1100 (c) 1300
  29. 29.Best estimate of 91 × 49? (a) 4500 (b) 450 (c) 45000
  30. 30.Best estimate of 608 + 512? (a) 1100 (b) 900 (c) 1300
  31. 31.Best estimate of 185 + 558? (a) 600 (b) 1000 (c) 800
  32. 32.Best estimate of 36 × 32? (a) 12000 (b) 1200 (c) 120
  33. 33.Best estimate of 539 + 203? (a) 900 (b) 700 (c) 500
  34. 34.Best estimate of 37 × 83? (a) 3200 (b) 32000 (c) 320
  35. 35.Best estimate of 851 + 599? (a) 1700 (b) 1300 (c) 1500
  36. 36.Best estimate of 87 × 69? (a) 6300 (b) 630 (c) 63000
  37. 37.Best estimate of 76 × 58? (a) 480 (b) 4800 (c) 48000
  38. 38.Best estimate of 145 + 156? (a) 500 (b) 100 (c) 300
  39. 39.Best estimate of 165 + 437? (a) 600 (b) 800 (c) 400
  40. 40.Best estimate of 16 × 32? (a) 600 (b) 60 (c) 6000

Answer key

  1. 4000
  2. 8100
  3. 2700
  4. 1200
  5. 1200
  6. 1400
  7. 4800
  8. 600
  9. 900
  10. 1000
  11. 1500
  12. 800
  13. 1200
  14. 1000
  15. 2000
  16. 8000
  17. 1400
  18. 600
  19. 3500
  20. 1600
  21. 1400
  22. 3000
  23. 1100
  24. 1500
  25. 600
  26. 1600
  27. 3500
  28. 1300
  29. 4500
  30. 1100
  31. 800
  32. 1200
  33. 700
  34. 3200
  35. 1500
  36. 6300
  37. 4800
  38. 300
  39. 600
  40. 600

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