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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 90 · 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 29 × 51? (a) 15000 (b) 150 (c) 1500
  2. 2.Best estimate of 505 + 360? (a) 700 (b) 1100 (c) 900
  3. 3.Best estimate of 149 + 810? (a) 900 (b) 700 (c) 1100
  4. 4.Best estimate of 643 + 823? (a) 1600 (b) 1200 (c) 1400
  5. 5.Best estimate of 78 × 53? (a) 40000 (b) 4000 (c) 400
  6. 6.Best estimate of 429 + 634? (a) 1000 (b) 1200 (c) 800
  7. 7.Best estimate of 251 + 199? (a) 700 (b) 500 (c) 300
  8. 8.Best estimate of 98 × 14? (a) 1000 (b) 100 (c) 10000
  9. 9.Best estimate of 14 × 72? (a) 70 (b) 700 (c) 7000
  10. 10.Best estimate of 57 × 18? (a) 1200 (b) 12000 (c) 120
  11. 11.Best estimate of 44 × 13? (a) 4000 (b) 400 (c) 40
  12. 12.Best estimate of 83 × 19? (a) 1600 (b) 160 (c) 16000
  13. 13.Best estimate of 37 × 63? (a) 240 (b) 2400 (c) 24000
  14. 14.Best estimate of 182 + 144? (a) 500 (b) 100 (c) 300
  15. 15.Best estimate of 87 × 30? (a) 27000 (b) 270 (c) 2700
  16. 16.Best estimate of 422 + 879? (a) 1300 (b) 1100 (c) 1500
  17. 17.Best estimate of 50 × 27? (a) 15000 (b) 150 (c) 1500
  18. 18.Best estimate of 363 + 664? (a) 1300 (b) 900 (c) 1100
  19. 19.Best estimate of 83 × 43? (a) 32000 (b) 3200 (c) 320
  20. 20.Best estimate of 97 × 26? (a) 3000 (b) 30000 (c) 300
  21. 21.Best estimate of 81 × 61? (a) 480 (b) 48000 (c) 4800
  22. 22.Best estimate of 96 × 30? (a) 3000 (b) 30000 (c) 300
  23. 23.Best estimate of 311 + 137? (a) 600 (b) 200 (c) 400
  24. 24.Best estimate of 608 + 565? (a) 1400 (b) 1200 (c) 1000
  25. 25.Best estimate of 66 × 39? (a) 2800 (b) 280 (c) 28000
  26. 26.Best estimate of 27 × 61? (a) 18000 (b) 180 (c) 1800
  27. 27.Best estimate of 96 × 74? (a) 7000 (b) 70000 (c) 700
  28. 28.Best estimate of 658 + 837? (a) 1500 (b) 1300 (c) 1700
  29. 29.Best estimate of 657 + 586? (a) 1100 (b) 1300 (c) 1500
  30. 30.Best estimate of 56 × 30? (a) 180 (b) 18000 (c) 1800
  31. 31.Best estimate of 295 + 520? (a) 800 (b) 1000 (c) 600
  32. 32.Best estimate of 21 × 57? (a) 12000 (b) 1200 (c) 120
  33. 33.Best estimate of 157 + 200? (a) 200 (b) 600 (c) 400
  34. 34.Best estimate of 56 × 54? (a) 300 (b) 30000 (c) 3000
  35. 35.Best estimate of 13 × 62? (a) 60 (b) 600 (c) 6000
  36. 36.Best estimate of 39 × 92? (a) 3600 (b) 36000 (c) 360
  37. 37.Best estimate of 76 × 63? (a) 480 (b) 48000 (c) 4800
  38. 38.Best estimate of 736 + 656? (a) 1400 (b) 1600 (c) 1200
  39. 39.Best estimate of 612 + 716? (a) 1500 (b) 1300 (c) 1100
  40. 40.Best estimate of 776 + 870? (a) 1500 (b) 1900 (c) 1700

Answer key

  1. 1500
  2. 900
  3. 900
  4. 1400
  5. 4000
  6. 1000
  7. 500
  8. 1000
  9. 700
  10. 1200
  11. 400
  12. 1600
  13. 2400
  14. 300
  15. 2700
  16. 1300
  17. 1500
  18. 1100
  19. 3200
  20. 3000
  21. 4800
  22. 3000
  23. 400
  24. 1200
  25. 2800
  26. 1800
  27. 7000
  28. 1500
  29. 1300
  30. 1800
  31. 800
  32. 1200
  33. 400
  34. 3000
  35. 600
  36. 3600
  37. 4800
  38. 1400
  39. 1300
  40. 1700

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