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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 398 · 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 652 + 446? (a) 900 (b) 1100 (c) 1300
  2. 2.Best estimate of 66 × 87? (a) 6300 (b) 630 (c) 63000
  3. 3.Best estimate of 230 + 788? (a) 800 (b) 1000 (c) 1200
  4. 4.Best estimate of 48 × 44? (a) 20000 (b) 200 (c) 2000
  5. 5.Best estimate of 49 × 22? (a) 10000 (b) 1000 (c) 100
  6. 6.Best estimate of 88 × 22? (a) 1800 (b) 180 (c) 18000
  7. 7.Best estimate of 24 × 82? (a) 1600 (b) 160 (c) 16000
  8. 8.Best estimate of 867 + 186? (a) 1300 (b) 900 (c) 1100
  9. 9.Best estimate of 36 × 40? (a) 1600 (b) 160 (c) 16000
  10. 10.Best estimate of 631 + 805? (a) 1600 (b) 1200 (c) 1400
  11. 11.Best estimate of 852 + 194? (a) 1100 (b) 900 (c) 1300
  12. 12.Best estimate of 36 × 56? (a) 24000 (b) 240 (c) 2400
  13. 13.Best estimate of 339 + 182? (a) 300 (b) 700 (c) 500
  14. 14.Best estimate of 92 × 67? (a) 630 (b) 6300 (c) 63000
  15. 15.Best estimate of 64 × 67? (a) 420 (b) 42000 (c) 4200
  16. 16.Best estimate of 87 × 86? (a) 8100 (b) 81000 (c) 810
  17. 17.Best estimate of 401 + 394? (a) 1000 (b) 800 (c) 600
  18. 18.Best estimate of 42 × 29? (a) 12000 (b) 120 (c) 1200
  19. 19.Best estimate of 27 × 71? (a) 2100 (b) 21000 (c) 210
  20. 20.Best estimate of 530 + 130? (a) 600 (b) 800 (c) 400
  21. 21.Best estimate of 24 × 47? (a) 1000 (b) 10000 (c) 100
  22. 22.Best estimate of 33 × 63? (a) 18000 (b) 1800 (c) 180
  23. 23.Best estimate of 26 × 51? (a) 150 (b) 1500 (c) 15000
  24. 24.Best estimate of 70 × 20? (a) 14000 (b) 1400 (c) 140
  25. 25.Best estimate of 866 + 695? (a) 1400 (b) 1800 (c) 1600
  26. 26.Best estimate of 84 × 69? (a) 5600 (b) 56000 (c) 560
  27. 27.Best estimate of 187 + 815? (a) 1000 (b) 1200 (c) 800
  28. 28.Best estimate of 752 + 284? (a) 900 (b) 1300 (c) 1100
  29. 29.Best estimate of 52 × 90? (a) 4500 (b) 45000 (c) 450
  30. 30.Best estimate of 140 + 575? (a) 900 (b) 500 (c) 700
  31. 31.Best estimate of 26 × 22? (a) 6000 (b) 600 (c) 60
  32. 32.Best estimate of 43 × 29? (a) 12000 (b) 120 (c) 1200
  33. 33.Best estimate of 56 × 24? (a) 12000 (b) 1200 (c) 120
  34. 34.Best estimate of 51 × 98? (a) 5000 (b) 50000 (c) 500
  35. 35.Best estimate of 296 + 308? (a) 600 (b) 800 (c) 400
  36. 36.Best estimate of 17 × 79? (a) 1600 (b) 160 (c) 16000
  37. 37.Best estimate of 63 × 92? (a) 540 (b) 54000 (c) 5400
  38. 38.Best estimate of 93 × 93? (a) 81000 (b) 810 (c) 8100
  39. 39.Best estimate of 373 + 351? (a) 600 (b) 800 (c) 1000
  40. 40.Best estimate of 23 × 70? (a) 1400 (b) 140 (c) 14000

Answer key

  1. 1100
  2. 6300
  3. 1000
  4. 2000
  5. 1000
  6. 1800
  7. 1600
  8. 1100
  9. 1600
  10. 1400
  11. 1100
  12. 2400
  13. 500
  14. 6300
  15. 4200
  16. 8100
  17. 800
  18. 1200
  19. 2100
  20. 600
  21. 1000
  22. 1800
  23. 1500
  24. 1400
  25. 1600
  26. 5600
  27. 1000
  28. 1100
  29. 4500
  30. 700
  31. 600
  32. 1200
  33. 1200
  34. 5000
  35. 600
  36. 1600
  37. 5400
  38. 8100
  39. 800
  40. 1400

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