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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 63 · 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 446 + 714? (a) 1300 (b) 1100 (c) 900
  2. 2.Best estimate of 37 × 33? (a) 12000 (b) 1200 (c) 120
  3. 3.Best estimate of 91 × 34? (a) 270 (b) 27000 (c) 2700
  4. 4.Best estimate of 517 + 594? (a) 1300 (b) 1100 (c) 900
  5. 5.Best estimate of 92 × 66? (a) 63000 (b) 630 (c) 6300
  6. 6.Best estimate of 533 + 673? (a) 1200 (b) 1400 (c) 1000
  7. 7.Best estimate of 62 × 51? (a) 30000 (b) 300 (c) 3000
  8. 8.Best estimate of 39 × 28? (a) 1200 (b) 120 (c) 12000
  9. 9.Best estimate of 323 + 817? (a) 1100 (b) 1300 (c) 900
  10. 10.Best estimate of 86 × 16? (a) 1800 (b) 18000 (c) 180
  11. 11.Best estimate of 79 × 86? (a) 72000 (b) 7200 (c) 720
  12. 12.Best estimate of 70 × 14? (a) 70 (b) 7000 (c) 700
  13. 13.Best estimate of 236 + 218? (a) 200 (b) 600 (c) 400
  14. 14.Best estimate of 28 × 50? (a) 150 (b) 1500 (c) 15000
  15. 15.Best estimate of 20 × 63? (a) 120 (b) 1200 (c) 12000
  16. 16.Best estimate of 96 × 27? (a) 3000 (b) 300 (c) 30000
  17. 17.Best estimate of 648 + 322? (a) 900 (b) 700 (c) 1100
  18. 18.Best estimate of 90 × 39? (a) 36000 (b) 3600 (c) 360
  19. 19.Best estimate of 205 + 703? (a) 900 (b) 1100 (c) 700
  20. 20.Best estimate of 696 + 316? (a) 800 (b) 1200 (c) 1000
  21. 21.Best estimate of 875 + 630? (a) 1300 (b) 1700 (c) 1500
  22. 22.Best estimate of 46 × 91? (a) 4500 (b) 450 (c) 45000
  23. 23.Best estimate of 49 × 50? (a) 250 (b) 2500 (c) 25000
  24. 24.Best estimate of 26 × 79? (a) 2400 (b) 240 (c) 24000
  25. 25.Best estimate of 614 + 759? (a) 1400 (b) 1200 (c) 1600
  26. 26.Best estimate of 26 × 16? (a) 60 (b) 6000 (c) 600
  27. 27.Best estimate of 17 × 28? (a) 600 (b) 6000 (c) 60
  28. 28.Best estimate of 80 × 23? (a) 16000 (b) 160 (c) 1600
  29. 29.Best estimate of 16 × 40? (a) 8000 (b) 800 (c) 80
  30. 30.Best estimate of 14 × 36? (a) 4000 (b) 400 (c) 40
  31. 31.Best estimate of 62 × 93? (a) 5400 (b) 540 (c) 54000
  32. 32.Best estimate of 24 × 13? (a) 2000 (b) 200 (c) 20
  33. 33.Best estimate of 62 × 49? (a) 300 (b) 30000 (c) 3000
  34. 34.Best estimate of 129 + 212? (a) 500 (b) 100 (c) 300
  35. 35.Best estimate of 78 × 50? (a) 4000 (b) 400 (c) 40000
  36. 36.Best estimate of 76 × 18? (a) 16000 (b) 160 (c) 1600
  37. 37.Best estimate of 86 × 92? (a) 810 (b) 8100 (c) 81000
  38. 38.Best estimate of 48 × 43? (a) 200 (b) 20000 (c) 2000
  39. 39.Best estimate of 73 × 53? (a) 3500 (b) 35000 (c) 350
  40. 40.Best estimate of 16 × 76? (a) 16000 (b) 1600 (c) 160

Answer key

  1. 1100
  2. 1200
  3. 2700
  4. 1100
  5. 6300
  6. 1200
  7. 3000
  8. 1200
  9. 1100
  10. 1800
  11. 7200
  12. 700
  13. 400
  14. 1500
  15. 1200
  16. 3000
  17. 900
  18. 3600
  19. 900
  20. 1000
  21. 1500
  22. 4500
  23. 2500
  24. 2400
  25. 1400
  26. 600
  27. 600
  28. 1600
  29. 800
  30. 400
  31. 5400
  32. 200
  33. 3000
  34. 300
  35. 4000
  36. 1600
  37. 8100
  38. 2000
  39. 3500
  40. 1600

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