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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 455 · 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 142 + 660? (a) 800 (b) 600 (c) 1000
  2. 2.Best estimate of 13 × 73? (a) 700 (b) 7000 (c) 70
  3. 3.Best estimate of 518 + 409? (a) 1100 (b) 900 (c) 700
  4. 4.Best estimate of 668 + 612? (a) 1300 (b) 1100 (c) 1500
  5. 5.Best estimate of 816 + 190? (a) 1000 (b) 1200 (c) 800
  6. 6.Best estimate of 44 × 87? (a) 3600 (b) 360 (c) 36000
  7. 7.Best estimate of 28 × 64? (a) 180 (b) 1800 (c) 18000
  8. 8.Best estimate of 66 × 36? (a) 28000 (b) 2800 (c) 280
  9. 9.Best estimate of 34 × 63? (a) 18000 (b) 1800 (c) 180
  10. 10.Best estimate of 59 × 57? (a) 3600 (b) 360 (c) 36000
  11. 11.Best estimate of 48 × 26? (a) 150 (b) 15000 (c) 1500
  12. 12.Best estimate of 30 × 49? (a) 1500 (b) 15000 (c) 150
  13. 13.Best estimate of 474 + 243? (a) 700 (b) 500 (c) 900
  14. 14.Best estimate of 154 + 292? (a) 500 (b) 700 (c) 300
  15. 15.Best estimate of 22 × 19? (a) 4000 (b) 40 (c) 400
  16. 16.Best estimate of 13 × 93? (a) 900 (b) 9000 (c) 90
  17. 17.Best estimate of 33 × 33? (a) 9000 (b) 90 (c) 900
  18. 18.Best estimate of 758 + 516? (a) 1500 (b) 1100 (c) 1300
  19. 19.Best estimate of 82 × 76? (a) 6400 (b) 64000 (c) 640
  20. 20.Best estimate of 38 × 60? (a) 240 (b) 2400 (c) 24000
  21. 21.Best estimate of 72 × 86? (a) 63000 (b) 630 (c) 6300
  22. 22.Best estimate of 46 × 52? (a) 25000 (b) 250 (c) 2500
  23. 23.Best estimate of 44 × 54? (a) 200 (b) 2000 (c) 20000
  24. 24.Best estimate of 20 × 77? (a) 16000 (b) 160 (c) 1600
  25. 25.Best estimate of 586 + 572? (a) 1400 (b) 1200 (c) 1000
  26. 26.Best estimate of 36 × 41? (a) 16000 (b) 1600 (c) 160
  27. 27.Best estimate of 632 + 274? (a) 900 (b) 700 (c) 1100
  28. 28.Best estimate of 86 × 49? (a) 450 (b) 45000 (c) 4500
  29. 29.Best estimate of 675 + 749? (a) 1200 (b) 1600 (c) 1400
  30. 30.Best estimate of 98 × 57? (a) 600 (b) 60000 (c) 6000
  31. 31.Best estimate of 186 + 256? (a) 500 (b) 700 (c) 300
  32. 32.Best estimate of 49 × 86? (a) 45000 (b) 4500 (c) 450
  33. 33.Best estimate of 91 × 89? (a) 810 (b) 81000 (c) 8100
  34. 34.Best estimate of 71 × 41? (a) 280 (b) 28000 (c) 2800
  35. 35.Best estimate of 748 + 464? (a) 1000 (b) 1400 (c) 1200
  36. 36.Best estimate of 27 × 27? (a) 9000 (b) 900 (c) 90
  37. 37.Best estimate of 566 + 368? (a) 1000 (b) 800 (c) 1200
  38. 38.Best estimate of 827 + 724? (a) 1500 (b) 1700 (c) 1300
  39. 39.Best estimate of 40 × 33? (a) 1200 (b) 12000 (c) 120
  40. 40.Best estimate of 89 × 54? (a) 450 (b) 45000 (c) 4500

Answer key

  1. 800
  2. 700
  3. 900
  4. 1300
  5. 1000
  6. 3600
  7. 1800
  8. 2800
  9. 1800
  10. 3600
  11. 1500
  12. 1500
  13. 700
  14. 500
  15. 400
  16. 900
  17. 900
  18. 1300
  19. 6400
  20. 2400
  21. 6300
  22. 2500
  23. 2000
  24. 1600
  25. 1200
  26. 1600
  27. 900
  28. 4500
  29. 1400
  30. 6000
  31. 500
  32. 4500
  33. 8100
  34. 2800
  35. 1200
  36. 900
  37. 1000
  38. 1500
  39. 1200
  40. 4500

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