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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 502 · 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 240 + 790? (a) 1200 (b) 1000 (c) 800
  2. 2.Best estimate of 84 × 18? (a) 1600 (b) 160 (c) 16000
  3. 3.Best estimate of 807 + 592? (a) 1400 (b) 1200 (c) 1600
  4. 4.Best estimate of 416 + 270? (a) 500 (b) 900 (c) 700
  5. 5.Best estimate of 40 × 13? (a) 400 (b) 4000 (c) 40
  6. 6.Best estimate of 93 × 77? (a) 7200 (b) 720 (c) 72000
  7. 7.Best estimate of 34 × 36? (a) 12000 (b) 120 (c) 1200
  8. 8.Best estimate of 690 + 536? (a) 1400 (b) 1000 (c) 1200
  9. 9.Best estimate of 92 × 93? (a) 8100 (b) 810 (c) 81000
  10. 10.Best estimate of 26 × 80? (a) 2400 (b) 240 (c) 24000
  11. 11.Best estimate of 53 × 19? (a) 1000 (b) 10000 (c) 100
  12. 12.Best estimate of 135 + 299? (a) 600 (b) 400 (c) 200
  13. 13.Best estimate of 321 + 740? (a) 800 (b) 1200 (c) 1000
  14. 14.Best estimate of 88 × 92? (a) 81000 (b) 810 (c) 8100
  15. 15.Best estimate of 93 × 81? (a) 720 (b) 7200 (c) 72000
  16. 16.Best estimate of 38 × 19? (a) 800 (b) 8000 (c) 80
  17. 17.Best estimate of 56 × 59? (a) 3600 (b) 360 (c) 36000
  18. 18.Best estimate of 72 × 26? (a) 2100 (b) 21000 (c) 210
  19. 19.Best estimate of 73 × 23? (a) 1400 (b) 14000 (c) 140
  20. 20.Best estimate of 93 × 64? (a) 54000 (b) 5400 (c) 540
  21. 21.Best estimate of 667 + 274? (a) 1000 (b) 1200 (c) 800
  22. 22.Best estimate of 17 × 34? (a) 60 (b) 600 (c) 6000
  23. 23.Best estimate of 54 × 86? (a) 45000 (b) 450 (c) 4500
  24. 24.Best estimate of 129 + 606? (a) 500 (b) 700 (c) 900
  25. 25.Best estimate of 719 + 751? (a) 1500 (b) 1700 (c) 1300
  26. 26.Best estimate of 365 + 284? (a) 900 (b) 700 (c) 500
  27. 27.Best estimate of 157 + 742? (a) 1100 (b) 700 (c) 900
  28. 28.Best estimate of 142 + 364? (a) 300 (b) 700 (c) 500
  29. 29.Best estimate of 653 + 739? (a) 1600 (b) 1400 (c) 1200
  30. 30.Best estimate of 32 × 16? (a) 60 (b) 600 (c) 6000
  31. 31.Best estimate of 308 + 330? (a) 600 (b) 400 (c) 800
  32. 32.Best estimate of 77 × 19? (a) 16000 (b) 1600 (c) 160
  33. 33.Best estimate of 849 + 498? (a) 1300 (b) 1500 (c) 1100
  34. 34.Best estimate of 845 + 147? (a) 900 (b) 700 (c) 1100
  35. 35.Best estimate of 84 × 59? (a) 48000 (b) 4800 (c) 480
  36. 36.Best estimate of 86 × 31? (a) 27000 (b) 270 (c) 2700
  37. 37.Best estimate of 14 × 43? (a) 400 (b) 4000 (c) 40
  38. 38.Best estimate of 18 × 90? (a) 18000 (b) 180 (c) 1800
  39. 39.Best estimate of 40 × 34? (a) 120 (b) 12000 (c) 1200
  40. 40.Best estimate of 803 + 684? (a) 1500 (b) 1700 (c) 1300

Answer key

  1. 1000
  2. 1600
  3. 1400
  4. 700
  5. 400
  6. 7200
  7. 1200
  8. 1200
  9. 8100
  10. 2400
  11. 1000
  12. 400
  13. 1000
  14. 8100
  15. 7200
  16. 800
  17. 3600
  18. 2100
  19. 1400
  20. 5400
  21. 1000
  22. 600
  23. 4500
  24. 700
  25. 1500
  26. 700
  27. 900
  28. 500
  29. 1400
  30. 600
  31. 600
  32. 1600
  33. 1300
  34. 900
  35. 4800
  36. 2700
  37. 400
  38. 1800
  39. 1200
  40. 1500

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