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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 685 · 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 94 × 86? (a) 810 (b) 81000 (c) 8100
  2. 2.Best estimate of 383 + 214? (a) 600 (b) 800 (c) 400
  3. 3.Best estimate of 33 × 50? (a) 1500 (b) 150 (c) 15000
  4. 4.Best estimate of 32 × 68? (a) 21000 (b) 2100 (c) 210
  5. 5.Best estimate of 14 × 83? (a) 80 (b) 8000 (c) 800
  6. 6.Best estimate of 148 + 677? (a) 800 (b) 1000 (c) 600
  7. 7.Best estimate of 685 + 443? (a) 900 (b) 1100 (c) 1300
  8. 8.Best estimate of 14 × 89? (a) 90 (b) 900 (c) 9000
  9. 9.Best estimate of 34 × 32? (a) 90 (b) 900 (c) 9000
  10. 10.Best estimate of 81 × 98? (a) 8000 (b) 80000 (c) 800
  11. 11.Best estimate of 176 + 844? (a) 1200 (b) 1000 (c) 800
  12. 12.Best estimate of 245 + 636? (a) 600 (b) 800 (c) 1000
  13. 13.Best estimate of 214 + 522? (a) 500 (b) 700 (c) 900
  14. 14.Best estimate of 297 + 876? (a) 1200 (b) 1400 (c) 1000
  15. 15.Best estimate of 40 × 59? (a) 24000 (b) 240 (c) 2400
  16. 16.Best estimate of 76 × 88? (a) 720 (b) 72000 (c) 7200
  17. 17.Best estimate of 185 + 208? (a) 600 (b) 400 (c) 200
  18. 18.Best estimate of 78 × 71? (a) 560 (b) 56000 (c) 5600
  19. 19.Best estimate of 226 + 253? (a) 700 (b) 500 (c) 300
  20. 20.Best estimate of 16 × 96? (a) 200 (b) 2000 (c) 20000
  21. 21.Best estimate of 60 × 74? (a) 4200 (b) 420 (c) 42000
  22. 22.Best estimate of 12 × 31? (a) 3000 (b) 300 (c) 30
  23. 23.Best estimate of 751 + 544? (a) 1300 (b) 1100 (c) 1500
  24. 24.Best estimate of 60 × 54? (a) 30000 (b) 300 (c) 3000
  25. 25.Best estimate of 81 × 20? (a) 1600 (b) 16000 (c) 160
  26. 26.Best estimate of 90 × 46? (a) 4500 (b) 450 (c) 45000
  27. 27.Best estimate of 819 + 676? (a) 1500 (b) 1700 (c) 1300
  28. 28.Best estimate of 34 × 92? (a) 2700 (b) 270 (c) 27000
  29. 29.Best estimate of 36 × 36? (a) 160 (b) 16000 (c) 1600
  30. 30.Best estimate of 83 × 17? (a) 1600 (b) 160 (c) 16000
  31. 31.Best estimate of 151 + 471? (a) 700 (b) 500 (c) 900
  32. 32.Best estimate of 96 × 24? (a) 20000 (b) 2000 (c) 200
  33. 33.Best estimate of 149 + 376? (a) 700 (b) 500 (c) 300
  34. 34.Best estimate of 499 + 356? (a) 700 (b) 1100 (c) 900
  35. 35.Best estimate of 30 × 70? (a) 2100 (b) 210 (c) 21000
  36. 36.Best estimate of 513 + 324? (a) 1000 (b) 600 (c) 800
  37. 37.Best estimate of 36 × 53? (a) 2000 (b) 200 (c) 20000
  38. 38.Best estimate of 485 + 316? (a) 1000 (b) 800 (c) 600
  39. 39.Best estimate of 34 × 34? (a) 900 (b) 90 (c) 9000
  40. 40.Best estimate of 92 × 61? (a) 54000 (b) 5400 (c) 540

Answer key

  1. 8100
  2. 600
  3. 1500
  4. 2100
  5. 800
  6. 800
  7. 1100
  8. 900
  9. 900
  10. 8000
  11. 1000
  12. 800
  13. 700
  14. 1200
  15. 2400
  16. 7200
  17. 400
  18. 5600
  19. 500
  20. 2000
  21. 4200
  22. 300
  23. 1300
  24. 3000
  25. 1600
  26. 4500
  27. 1500
  28. 2700
  29. 1600
  30. 1600
  31. 700
  32. 2000
  33. 500
  34. 900
  35. 2100
  36. 800
  37. 2000
  38. 800
  39. 900
  40. 5400

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