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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 391 · 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 368 + 341? (a) 700 (b) 500 (c) 900
  2. 2.Best estimate of 53 × 97? (a) 5000 (b) 500 (c) 50000
  3. 3.Best estimate of 27 × 33? (a) 90 (b) 9000 (c) 900
  4. 4.Best estimate of 87 × 53? (a) 4500 (b) 450 (c) 45000
  5. 5.Best estimate of 19 × 18? (a) 4000 (b) 400 (c) 40
  6. 6.Best estimate of 160 + 802? (a) 1200 (b) 800 (c) 1000
  7. 7.Best estimate of 16 × 43? (a) 8000 (b) 800 (c) 80
  8. 8.Best estimate of 831 + 599? (a) 1400 (b) 1600 (c) 1200
  9. 9.Best estimate of 33 × 61? (a) 18000 (b) 1800 (c) 180
  10. 10.Best estimate of 602 + 275? (a) 700 (b) 1100 (c) 900
  11. 11.Best estimate of 23 × 46? (a) 100 (b) 10000 (c) 1000
  12. 12.Best estimate of 36 × 33? (a) 120 (b) 12000 (c) 1200
  13. 13.Best estimate of 46 × 19? (a) 10000 (b) 100 (c) 1000
  14. 14.Best estimate of 20 × 33? (a) 60 (b) 6000 (c) 600
  15. 15.Best estimate of 87 × 72? (a) 63000 (b) 630 (c) 6300
  16. 16.Best estimate of 41 × 28? (a) 12000 (b) 1200 (c) 120
  17. 17.Best estimate of 49 × 16? (a) 100 (b) 1000 (c) 10000
  18. 18.Best estimate of 16 × 38? (a) 80 (b) 800 (c) 8000
  19. 19.Best estimate of 80 × 22? (a) 160 (b) 1600 (c) 16000
  20. 20.Best estimate of 244 + 562? (a) 1000 (b) 800 (c) 600
  21. 21.Best estimate of 80 × 73? (a) 5600 (b) 56000 (c) 560
  22. 22.Best estimate of 878 + 331? (a) 1000 (b) 1200 (c) 1400
  23. 23.Best estimate of 51 × 71? (a) 35000 (b) 3500 (c) 350
  24. 24.Best estimate of 34 × 86? (a) 270 (b) 27000 (c) 2700
  25. 25.Best estimate of 387 + 446? (a) 800 (b) 1000 (c) 600
  26. 26.Best estimate of 62 × 50? (a) 30000 (b) 300 (c) 3000
  27. 27.Best estimate of 392 + 447? (a) 600 (b) 1000 (c) 800
  28. 28.Best estimate of 90 × 61? (a) 54000 (b) 540 (c) 5400
  29. 29.Best estimate of 60 × 88? (a) 5400 (b) 540 (c) 54000
  30. 30.Best estimate of 41 × 72? (a) 280 (b) 28000 (c) 2800
  31. 31.Best estimate of 27 × 98? (a) 3000 (b) 30000 (c) 300
  32. 32.Best estimate of 147 + 682? (a) 800 (b) 600 (c) 1000
  33. 33.Best estimate of 56 × 80? (a) 4800 (b) 48000 (c) 480
  34. 34.Best estimate of 21 × 48? (a) 1000 (b) 10000 (c) 100
  35. 35.Best estimate of 79 × 74? (a) 5600 (b) 56000 (c) 560
  36. 36.Best estimate of 245 + 825? (a) 800 (b) 1200 (c) 1000
  37. 37.Best estimate of 12 × 42? (a) 400 (b) 4000 (c) 40
  38. 38.Best estimate of 22 × 16? (a) 400 (b) 4000 (c) 40
  39. 39.Best estimate of 704 + 151? (a) 900 (b) 700 (c) 1100
  40. 40.Best estimate of 282 + 460? (a) 800 (b) 1000 (c) 600

Answer key

  1. 700
  2. 5000
  3. 900
  4. 4500
  5. 400
  6. 1000
  7. 800
  8. 1400
  9. 1800
  10. 900
  11. 1000
  12. 1200
  13. 1000
  14. 600
  15. 6300
  16. 1200
  17. 1000
  18. 800
  19. 1600
  20. 800
  21. 5600
  22. 1200
  23. 3500
  24. 2700
  25. 800
  26. 3000
  27. 800
  28. 5400
  29. 5400
  30. 2800
  31. 3000
  32. 800
  33. 4800
  34. 1000
  35. 5600
  36. 1000
  37. 400
  38. 400
  39. 900
  40. 800

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