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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 515 · 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 77 × 37? (a) 32000 (b) 3200 (c) 320
  2. 2.Best estimate of 649 + 561? (a) 1400 (b) 1000 (c) 1200
  3. 3.Best estimate of 77 × 57? (a) 480 (b) 48000 (c) 4800
  4. 4.Best estimate of 719 + 601? (a) 1100 (b) 1300 (c) 1500
  5. 5.Best estimate of 794 + 642? (a) 1600 (b) 1200 (c) 1400
  6. 6.Best estimate of 19 × 24? (a) 400 (b) 40 (c) 4000
  7. 7.Best estimate of 851 + 615? (a) 1500 (b) 1700 (c) 1300
  8. 8.Best estimate of 70 × 53? (a) 3500 (b) 350 (c) 35000
  9. 9.Best estimate of 59 × 62? (a) 3600 (b) 360 (c) 36000
  10. 10.Best estimate of 465 + 595? (a) 900 (b) 1100 (c) 1300
  11. 11.Best estimate of 24 × 86? (a) 1800 (b) 18000 (c) 180
  12. 12.Best estimate of 859 + 665? (a) 1600 (b) 1800 (c) 1400
  13. 13.Best estimate of 96 × 86? (a) 90000 (b) 900 (c) 9000
  14. 14.Best estimate of 145 + 868? (a) 1000 (b) 800 (c) 1200
  15. 15.Best estimate of 801 + 436? (a) 1400 (b) 1200 (c) 1000
  16. 16.Best estimate of 586 + 356? (a) 800 (b) 1000 (c) 1200
  17. 17.Best estimate of 805 + 499? (a) 1300 (b) 1500 (c) 1100
  18. 18.Best estimate of 94 × 97? (a) 90000 (b) 900 (c) 9000
  19. 19.Best estimate of 148 + 464? (a) 800 (b) 600 (c) 400
  20. 20.Best estimate of 460 + 551? (a) 1300 (b) 900 (c) 1100
  21. 21.Best estimate of 44 × 22? (a) 8000 (b) 800 (c) 80
  22. 22.Best estimate of 63 × 31? (a) 1800 (b) 18000 (c) 180
  23. 23.Best estimate of 430 + 613? (a) 1000 (b) 800 (c) 1200
  24. 24.Best estimate of 94 × 49? (a) 450 (b) 45000 (c) 4500
  25. 25.Best estimate of 168 + 204? (a) 200 (b) 600 (c) 400
  26. 26.Best estimate of 52 × 80? (a) 40000 (b) 400 (c) 4000
  27. 27.Best estimate of 87 × 20? (a) 1800 (b) 180 (c) 18000
  28. 28.Best estimate of 602 + 262? (a) 700 (b) 1100 (c) 900
  29. 29.Best estimate of 21 × 84? (a) 160 (b) 1600 (c) 16000
  30. 30.Best estimate of 41 × 92? (a) 36000 (b) 3600 (c) 360
  31. 31.Best estimate of 44 × 29? (a) 12000 (b) 1200 (c) 120
  32. 32.Best estimate of 82 × 74? (a) 56000 (b) 5600 (c) 560
  33. 33.Best estimate of 20 × 27? (a) 6000 (b) 60 (c) 600
  34. 34.Best estimate of 141 + 120? (a) 400 (b) 200 (c) 0
  35. 35.Best estimate of 64 × 98? (a) 60000 (b) 6000 (c) 600
  36. 36.Best estimate of 59 × 14? (a) 600 (b) 6000 (c) 60
  37. 37.Best estimate of 134 + 212? (a) 500 (b) 300 (c) 100
  38. 38.Best estimate of 345 + 286? (a) 600 (b) 800 (c) 400
  39. 39.Best estimate of 305 + 436? (a) 500 (b) 900 (c) 700
  40. 40.Best estimate of 64 × 43? (a) 24000 (b) 2400 (c) 240

Answer key

  1. 3200
  2. 1200
  3. 4800
  4. 1300
  5. 1400
  6. 400
  7. 1500
  8. 3500
  9. 3600
  10. 1100
  11. 1800
  12. 1600
  13. 9000
  14. 1000
  15. 1200
  16. 1000
  17. 1300
  18. 9000
  19. 600
  20. 1100
  21. 800
  22. 1800
  23. 1000
  24. 4500
  25. 400
  26. 4000
  27. 1800
  28. 900
  29. 1600
  30. 3600
  31. 1200
  32. 5600
  33. 600
  34. 200
  35. 6000
  36. 600
  37. 300
  38. 600
  39. 700
  40. 2400

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