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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 260 · 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 78 × 61? (a) 48000 (b) 4800 (c) 480
  2. 2.Best estimate of 66 × 12? (a) 7000 (b) 700 (c) 70
  3. 3.Best estimate of 36 × 58? (a) 240 (b) 2400 (c) 24000
  4. 4.Best estimate of 52 × 69? (a) 3500 (b) 35000 (c) 350
  5. 5.Best estimate of 50 × 66? (a) 35000 (b) 350 (c) 3500
  6. 6.Best estimate of 64 × 88? (a) 540 (b) 54000 (c) 5400
  7. 7.Best estimate of 806 + 148? (a) 700 (b) 900 (c) 1100
  8. 8.Best estimate of 82 × 98? (a) 800 (b) 8000 (c) 80000
  9. 9.Best estimate of 16 × 36? (a) 800 (b) 80 (c) 8000
  10. 10.Best estimate of 78 × 52? (a) 40000 (b) 4000 (c) 400
  11. 11.Best estimate of 50 × 43? (a) 200 (b) 2000 (c) 20000
  12. 12.Best estimate of 19 × 37? (a) 8000 (b) 800 (c) 80
  13. 13.Best estimate of 847 + 448? (a) 1400 (b) 1000 (c) 1200
  14. 14.Best estimate of 12 × 56? (a) 6000 (b) 60 (c) 600
  15. 15.Best estimate of 22 × 84? (a) 1600 (b) 16000 (c) 160
  16. 16.Best estimate of 269 + 285? (a) 800 (b) 600 (c) 400
  17. 17.Best estimate of 140 + 690? (a) 1000 (b) 600 (c) 800
  18. 18.Best estimate of 846 + 337? (a) 1300 (b) 1100 (c) 900
  19. 19.Best estimate of 91 × 20? (a) 180 (b) 1800 (c) 18000
  20. 20.Best estimate of 88 × 52? (a) 45000 (b) 450 (c) 4500
  21. 21.Best estimate of 335 + 184? (a) 700 (b) 500 (c) 300
  22. 22.Best estimate of 39 × 19? (a) 8000 (b) 800 (c) 80
  23. 23.Best estimate of 431 + 823? (a) 1400 (b) 1200 (c) 1000
  24. 24.Best estimate of 735 + 555? (a) 1300 (b) 1500 (c) 1100
  25. 25.Best estimate of 72 × 82? (a) 56000 (b) 5600 (c) 560
  26. 26.Best estimate of 492 + 212? (a) 500 (b) 900 (c) 700
  27. 27.Best estimate of 213 + 424? (a) 800 (b) 600 (c) 400
  28. 28.Best estimate of 14 × 14? (a) 10 (b) 1000 (c) 100
  29. 29.Best estimate of 560 + 661? (a) 1500 (b) 1300 (c) 1100
  30. 30.Best estimate of 234 + 830? (a) 1200 (b) 800 (c) 1000
  31. 31.Best estimate of 628 + 453? (a) 900 (b) 1300 (c) 1100
  32. 32.Best estimate of 42 × 86? (a) 360 (b) 3600 (c) 36000
  33. 33.Best estimate of 43 × 29? (a) 1200 (b) 12000 (c) 120
  34. 34.Best estimate of 59 × 68? (a) 42000 (b) 4200 (c) 420
  35. 35.Best estimate of 327 + 414? (a) 900 (b) 500 (c) 700
  36. 36.Best estimate of 64 × 16? (a) 1200 (b) 120 (c) 12000
  37. 37.Best estimate of 30 × 53? (a) 1500 (b) 150 (c) 15000
  38. 38.Best estimate of 447 + 684? (a) 900 (b) 1100 (c) 1300
  39. 39.Best estimate of 54 × 56? (a) 300 (b) 3000 (c) 30000
  40. 40.Best estimate of 19 × 92? (a) 1800 (b) 180 (c) 18000

Answer key

  1. 4800
  2. 700
  3. 2400
  4. 3500
  5. 3500
  6. 5400
  7. 900
  8. 8000
  9. 800
  10. 4000
  11. 2000
  12. 800
  13. 1200
  14. 600
  15. 1600
  16. 600
  17. 800
  18. 1100
  19. 1800
  20. 4500
  21. 500
  22. 800
  23. 1200
  24. 1300
  25. 5600
  26. 700
  27. 600
  28. 100
  29. 1300
  30. 1000
  31. 1100
  32. 3600
  33. 1200
  34. 4200
  35. 700
  36. 1200
  37. 1500
  38. 1100
  39. 3000
  40. 1800

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