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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 753 · 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 482 + 517? (a) 1200 (b) 1000 (c) 800
  2. 2.Best estimate of 26 × 66? (a) 210 (b) 2100 (c) 21000
  3. 3.Best estimate of 56 × 26? (a) 180 (b) 18000 (c) 1800
  4. 4.Best estimate of 189 + 593? (a) 600 (b) 1000 (c) 800
  5. 5.Best estimate of 300 + 133? (a) 600 (b) 400 (c) 200
  6. 6.Best estimate of 518 + 817? (a) 1300 (b) 1100 (c) 1500
  7. 7.Best estimate of 88 × 17? (a) 1800 (b) 18000 (c) 180
  8. 8.Best estimate of 733 + 665? (a) 1400 (b) 1200 (c) 1600
  9. 9.Best estimate of 48 × 74? (a) 350 (b) 3500 (c) 35000
  10. 10.Best estimate of 74 × 57? (a) 4200 (b) 42000 (c) 420
  11. 11.Best estimate of 661 + 412? (a) 900 (b) 1300 (c) 1100
  12. 12.Best estimate of 66 × 87? (a) 6300 (b) 63000 (c) 630
  13. 13.Best estimate of 57 × 52? (a) 30000 (b) 3000 (c) 300
  14. 14.Best estimate of 40 × 32? (a) 120 (b) 12000 (c) 1200
  15. 15.Best estimate of 606 + 167? (a) 800 (b) 600 (c) 1000
  16. 16.Best estimate of 28 × 27? (a) 9000 (b) 900 (c) 90
  17. 17.Best estimate of 29 × 47? (a) 1500 (b) 150 (c) 15000
  18. 18.Best estimate of 20 × 69? (a) 140 (b) 1400 (c) 14000
  19. 19.Best estimate of 725 + 255? (a) 800 (b) 1200 (c) 1000
  20. 20.Best estimate of 82 × 24? (a) 1600 (b) 160 (c) 16000
  21. 21.Best estimate of 814 + 703? (a) 1300 (b) 1500 (c) 1700
  22. 22.Best estimate of 26 × 91? (a) 27000 (b) 2700 (c) 270
  23. 23.Best estimate of 34 × 16? (a) 600 (b) 60 (c) 6000
  24. 24.Best estimate of 43 × 32? (a) 120 (b) 12000 (c) 1200
  25. 25.Best estimate of 238 + 270? (a) 300 (b) 500 (c) 700
  26. 26.Best estimate of 18 × 61? (a) 1200 (b) 12000 (c) 120
  27. 27.Best estimate of 306 + 209? (a) 300 (b) 700 (c) 500
  28. 28.Best estimate of 88 × 46? (a) 4500 (b) 45000 (c) 450
  29. 29.Best estimate of 856 + 633? (a) 1700 (b) 1500 (c) 1300
  30. 30.Best estimate of 18 × 80? (a) 16000 (b) 160 (c) 1600
  31. 31.Best estimate of 804 + 165? (a) 800 (b) 1200 (c) 1000
  32. 32.Best estimate of 137 + 134? (a) 400 (b) 200 (c) 0
  33. 33.Best estimate of 96 × 19? (a) 20000 (b) 200 (c) 2000
  34. 34.Best estimate of 59 × 46? (a) 30000 (b) 3000 (c) 300
  35. 35.Best estimate of 29 × 28? (a) 90 (b) 900 (c) 9000
  36. 36.Best estimate of 451 + 161? (a) 900 (b) 700 (c) 500
  37. 37.Best estimate of 28 × 16? (a) 6000 (b) 600 (c) 60
  38. 38.Best estimate of 303 + 396? (a) 700 (b) 900 (c) 500
  39. 39.Best estimate of 72 × 71? (a) 49000 (b) 490 (c) 4900
  40. 40.Best estimate of 96 × 96? (a) 10000 (b) 1000 (c) 100000

Answer key

  1. 1000
  2. 2100
  3. 1800
  4. 800
  5. 400
  6. 1300
  7. 1800
  8. 1400
  9. 3500
  10. 4200
  11. 1100
  12. 6300
  13. 3000
  14. 1200
  15. 800
  16. 900
  17. 1500
  18. 1400
  19. 1000
  20. 1600
  21. 1500
  22. 2700
  23. 600
  24. 1200
  25. 500
  26. 1200
  27. 500
  28. 4500
  29. 1500
  30. 1600
  31. 1000
  32. 200
  33. 2000
  34. 3000
  35. 900
  36. 700
  37. 600
  38. 700
  39. 4900
  40. 10000

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