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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 484 · 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 93 × 27? (a) 27000 (b) 2700 (c) 270
  2. 2.Best estimate of 277 + 792? (a) 900 (b) 1100 (c) 1300
  3. 3.Best estimate of 37 × 79? (a) 3200 (b) 320 (c) 32000
  4. 4.Best estimate of 78 × 17? (a) 160 (b) 16000 (c) 1600
  5. 5.Best estimate of 578 + 142? (a) 500 (b) 700 (c) 900
  6. 6.Best estimate of 320 + 722? (a) 800 (b) 1000 (c) 1200
  7. 7.Best estimate of 46 × 51? (a) 2500 (b) 25000 (c) 250
  8. 8.Best estimate of 36 × 24? (a) 8000 (b) 80 (c) 800
  9. 9.Best estimate of 77 × 94? (a) 72000 (b) 7200 (c) 720
  10. 10.Best estimate of 32 × 62? (a) 180 (b) 18000 (c) 1800
  11. 11.Best estimate of 46 × 32? (a) 15000 (b) 150 (c) 1500
  12. 12.Best estimate of 70 × 91? (a) 630 (b) 63000 (c) 6300
  13. 13.Best estimate of 713 + 221? (a) 1100 (b) 900 (c) 700
  14. 14.Best estimate of 50 × 46? (a) 25000 (b) 2500 (c) 250
  15. 15.Best estimate of 30 × 22? (a) 60 (b) 600 (c) 6000
  16. 16.Best estimate of 90 × 92? (a) 81000 (b) 810 (c) 8100
  17. 17.Best estimate of 286 + 596? (a) 700 (b) 900 (c) 1100
  18. 18.Best estimate of 487 + 739? (a) 1400 (b) 1200 (c) 1000
  19. 19.Best estimate of 324 + 311? (a) 400 (b) 800 (c) 600
  20. 20.Best estimate of 589 + 653? (a) 1300 (b) 1500 (c) 1100
  21. 21.Best estimate of 29 × 20? (a) 600 (b) 60 (c) 6000
  22. 22.Best estimate of 383 + 816? (a) 1400 (b) 1000 (c) 1200
  23. 23.Best estimate of 89 × 62? (a) 54000 (b) 540 (c) 5400
  24. 24.Best estimate of 23 × 19? (a) 40 (b) 4000 (c) 400
  25. 25.Best estimate of 487 + 878? (a) 1200 (b) 1400 (c) 1600
  26. 26.Best estimate of 14 × 26? (a) 30 (b) 3000 (c) 300
  27. 27.Best estimate of 18 × 56? (a) 1200 (b) 12000 (c) 120
  28. 28.Best estimate of 710 + 295? (a) 800 (b) 1000 (c) 1200
  29. 29.Best estimate of 23 × 23? (a) 400 (b) 40 (c) 4000
  30. 30.Best estimate of 96 × 73? (a) 700 (b) 7000 (c) 70000
  31. 31.Best estimate of 401 + 207? (a) 400 (b) 800 (c) 600
  32. 32.Best estimate of 122 + 702? (a) 800 (b) 600 (c) 1000
  33. 33.Best estimate of 696 + 613? (a) 1500 (b) 1100 (c) 1300
  34. 34.Best estimate of 300 + 364? (a) 500 (b) 900 (c) 700
  35. 35.Best estimate of 41 × 49? (a) 200 (b) 2000 (c) 20000
  36. 36.Best estimate of 62 × 64? (a) 3600 (b) 36000 (c) 360
  37. 37.Best estimate of 541 + 338? (a) 1000 (b) 800 (c) 600
  38. 38.Best estimate of 48 × 20? (a) 1000 (b) 10000 (c) 100
  39. 39.Best estimate of 695 + 270? (a) 1000 (b) 800 (c) 1200
  40. 40.Best estimate of 212 + 346? (a) 500 (b) 700 (c) 300

Answer key

  1. 2700
  2. 1100
  3. 3200
  4. 1600
  5. 700
  6. 1000
  7. 2500
  8. 800
  9. 7200
  10. 1800
  11. 1500
  12. 6300
  13. 900
  14. 2500
  15. 600
  16. 8100
  17. 900
  18. 1200
  19. 600
  20. 1300
  21. 600
  22. 1200
  23. 5400
  24. 400
  25. 1400
  26. 300
  27. 1200
  28. 1000
  29. 400
  30. 7000
  31. 600
  32. 800
  33. 1300
  34. 700
  35. 2000
  36. 3600
  37. 800
  38. 1000
  39. 1000
  40. 500

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