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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 813 · 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 79 × 61? (a) 48000 (b) 480 (c) 4800
  2. 2.Best estimate of 80 × 66? (a) 5600 (b) 56000 (c) 560
  3. 3.Best estimate of 46 × 43? (a) 2000 (b) 20000 (c) 200
  4. 4.Best estimate of 67 × 57? (a) 42000 (b) 420 (c) 4200
  5. 5.Best estimate of 284 + 520? (a) 1000 (b) 800 (c) 600
  6. 6.Best estimate of 693 + 746? (a) 1600 (b) 1400 (c) 1200
  7. 7.Best estimate of 43 × 33? (a) 1200 (b) 120 (c) 12000
  8. 8.Best estimate of 207 + 541? (a) 700 (b) 900 (c) 500
  9. 9.Best estimate of 714 + 800? (a) 1500 (b) 1700 (c) 1300
  10. 10.Best estimate of 26 × 31? (a) 90 (b) 900 (c) 9000
  11. 11.Best estimate of 88 × 98? (a) 900 (b) 90000 (c) 9000
  12. 12.Best estimate of 73 × 96? (a) 70000 (b) 700 (c) 7000
  13. 13.Best estimate of 36 × 26? (a) 120 (b) 1200 (c) 12000
  14. 14.Best estimate of 326 + 220? (a) 500 (b) 700 (c) 300
  15. 15.Best estimate of 524 + 877? (a) 1600 (b) 1400 (c) 1200
  16. 16.Best estimate of 50 × 87? (a) 45000 (b) 450 (c) 4500
  17. 17.Best estimate of 286 + 788? (a) 1300 (b) 1100 (c) 900
  18. 18.Best estimate of 188 + 861? (a) 900 (b) 1100 (c) 1300
  19. 19.Best estimate of 30 × 60? (a) 1800 (b) 180 (c) 18000
  20. 20.Best estimate of 49 × 49? (a) 2500 (b) 25000 (c) 250
  21. 21.Best estimate of 86 × 92? (a) 810 (b) 81000 (c) 8100
  22. 22.Best estimate of 862 + 341? (a) 1200 (b) 1000 (c) 1400
  23. 23.Best estimate of 38 × 98? (a) 400 (b) 40000 (c) 4000
  24. 24.Best estimate of 675 + 419? (a) 900 (b) 1100 (c) 1300
  25. 25.Best estimate of 21 × 17? (a) 40 (b) 400 (c) 4000
  26. 26.Best estimate of 56 × 32? (a) 180 (b) 18000 (c) 1800
  27. 27.Best estimate of 68 × 27? (a) 21000 (b) 2100 (c) 210
  28. 28.Best estimate of 39 × 90? (a) 360 (b) 36000 (c) 3600
  29. 29.Best estimate of 61 × 26? (a) 1800 (b) 180 (c) 18000
  30. 30.Best estimate of 364 + 335? (a) 500 (b) 900 (c) 700
  31. 31.Best estimate of 90 × 47? (a) 45000 (b) 450 (c) 4500
  32. 32.Best estimate of 88 × 96? (a) 90000 (b) 900 (c) 9000
  33. 33.Best estimate of 18 × 76? (a) 16000 (b) 160 (c) 1600
  34. 34.Best estimate of 83 × 86? (a) 7200 (b) 72000 (c) 720
  35. 35.Best estimate of 318 + 778? (a) 1100 (b) 1300 (c) 900
  36. 36.Best estimate of 22 × 89? (a) 1800 (b) 18000 (c) 180
  37. 37.Best estimate of 56 × 80? (a) 4800 (b) 480 (c) 48000
  38. 38.Best estimate of 23 × 20? (a) 400 (b) 4000 (c) 40
  39. 39.Best estimate of 28 × 70? (a) 210 (b) 2100 (c) 21000
  40. 40.Best estimate of 682 + 832? (a) 1300 (b) 1500 (c) 1700

Answer key

  1. 4800
  2. 5600
  3. 2000
  4. 4200
  5. 800
  6. 1400
  7. 1200
  8. 700
  9. 1500
  10. 900
  11. 9000
  12. 7000
  13. 1200
  14. 500
  15. 1400
  16. 4500
  17. 1100
  18. 1100
  19. 1800
  20. 2500
  21. 8100
  22. 1200
  23. 4000
  24. 1100
  25. 400
  26. 1800
  27. 2100
  28. 3600
  29. 1800
  30. 700
  31. 4500
  32. 9000
  33. 1600
  34. 7200
  35. 1100
  36. 1800
  37. 4800
  38. 400
  39. 2100
  40. 1500

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