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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 220 · 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 677 + 131? (a) 600 (b) 800 (c) 1000
  2. 2.Best estimate of 31 × 92? (a) 270 (b) 27000 (c) 2700
  3. 3.Best estimate of 91 × 20? (a) 18000 (b) 1800 (c) 180
  4. 4.Best estimate of 295 + 194? (a) 300 (b) 500 (c) 700
  5. 5.Best estimate of 60 × 56? (a) 360 (b) 36000 (c) 3600
  6. 6.Best estimate of 437 + 603? (a) 1000 (b) 1200 (c) 800
  7. 7.Best estimate of 42 × 43? (a) 16000 (b) 1600 (c) 160
  8. 8.Best estimate of 796 + 473? (a) 1100 (b) 1500 (c) 1300
  9. 9.Best estimate of 44 × 87? (a) 36000 (b) 3600 (c) 360
  10. 10.Best estimate of 331 + 210? (a) 300 (b) 500 (c) 700
  11. 11.Best estimate of 59 × 88? (a) 5400 (b) 540 (c) 54000
  12. 12.Best estimate of 176 + 848? (a) 1000 (b) 1200 (c) 800
  13. 13.Best estimate of 34 × 98? (a) 30000 (b) 300 (c) 3000
  14. 14.Best estimate of 277 + 760? (a) 1300 (b) 900 (c) 1100
  15. 15.Best estimate of 131 + 183? (a) 500 (b) 300 (c) 100
  16. 16.Best estimate of 66 × 54? (a) 35000 (b) 350 (c) 3500
  17. 17.Best estimate of 13 × 86? (a) 900 (b) 9000 (c) 90
  18. 18.Best estimate of 220 + 217? (a) 600 (b) 200 (c) 400
  19. 19.Best estimate of 61 × 72? (a) 4200 (b) 420 (c) 42000
  20. 20.Best estimate of 73 × 94? (a) 6300 (b) 630 (c) 63000
  21. 21.Best estimate of 697 + 752? (a) 1500 (b) 1700 (c) 1300
  22. 22.Best estimate of 176 + 242? (a) 400 (b) 200 (c) 600
  23. 23.Best estimate of 34 × 50? (a) 150 (b) 15000 (c) 1500
  24. 24.Best estimate of 448 + 612? (a) 1000 (b) 800 (c) 1200
  25. 25.Best estimate of 303 + 596? (a) 1100 (b) 700 (c) 900
  26. 26.Best estimate of 46 × 96? (a) 500 (b) 50000 (c) 5000
  27. 27.Best estimate of 341 + 853? (a) 1200 (b) 1400 (c) 1000
  28. 28.Best estimate of 78 × 49? (a) 4000 (b) 400 (c) 40000
  29. 29.Best estimate of 49 × 46? (a) 2500 (b) 25000 (c) 250
  30. 30.Best estimate of 634 + 182? (a) 800 (b) 1000 (c) 600
  31. 31.Best estimate of 67 × 47? (a) 35000 (b) 3500 (c) 350
  32. 32.Best estimate of 39 × 16? (a) 80 (b) 8000 (c) 800
  33. 33.Best estimate of 430 + 329? (a) 500 (b) 900 (c) 700
  34. 34.Best estimate of 695 + 813? (a) 1300 (b) 1700 (c) 1500
  35. 35.Best estimate of 48 × 71? (a) 35000 (b) 350 (c) 3500
  36. 36.Best estimate of 94 × 98? (a) 9000 (b) 90000 (c) 900
  37. 37.Best estimate of 328 + 265? (a) 800 (b) 600 (c) 400
  38. 38.Best estimate of 358 + 194? (a) 400 (b) 800 (c) 600
  39. 39.Best estimate of 18 × 54? (a) 100 (b) 1000 (c) 10000
  40. 40.Best estimate of 759 + 274? (a) 900 (b) 1300 (c) 1100

Answer key

  1. 800
  2. 2700
  3. 1800
  4. 500
  5. 3600
  6. 1000
  7. 1600
  8. 1300
  9. 3600
  10. 500
  11. 5400
  12. 1000
  13. 3000
  14. 1100
  15. 300
  16. 3500
  17. 900
  18. 400
  19. 4200
  20. 6300
  21. 1500
  22. 400
  23. 1500
  24. 1000
  25. 900
  26. 5000
  27. 1200
  28. 4000
  29. 2500
  30. 800
  31. 3500
  32. 800
  33. 700
  34. 1500
  35. 3500
  36. 9000
  37. 600
  38. 600
  39. 1000
  40. 1100

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