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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 417 · 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 59 × 22? (a) 12000 (b) 120 (c) 1200
  2. 2.Best estimate of 89 × 19? (a) 18000 (b) 180 (c) 1800
  3. 3.Best estimate of 294 + 251? (a) 600 (b) 800 (c) 400
  4. 4.Best estimate of 351 + 137? (a) 500 (b) 300 (c) 700
  5. 5.Best estimate of 84 × 66? (a) 560 (b) 5600 (c) 56000
  6. 6.Best estimate of 187 + 711? (a) 1100 (b) 900 (c) 700
  7. 7.Best estimate of 98 × 96? (a) 100000 (b) 1000 (c) 10000
  8. 8.Best estimate of 57 × 59? (a) 3600 (b) 36000 (c) 360
  9. 9.Best estimate of 797 + 667? (a) 1700 (b) 1500 (c) 1300
  10. 10.Best estimate of 29 × 96? (a) 30000 (b) 3000 (c) 300
  11. 11.Best estimate of 436 + 253? (a) 500 (b) 900 (c) 700
  12. 12.Best estimate of 270 + 272? (a) 600 (b) 400 (c) 800
  13. 13.Best estimate of 161 + 705? (a) 900 (b) 700 (c) 1100
  14. 14.Best estimate of 52 × 53? (a) 2500 (b) 25000 (c) 250
  15. 15.Best estimate of 19 × 80? (a) 1600 (b) 160 (c) 16000
  16. 16.Best estimate of 64 × 90? (a) 5400 (b) 54000 (c) 540
  17. 17.Best estimate of 57 × 14? (a) 600 (b) 6000 (c) 60
  18. 18.Best estimate of 76 × 67? (a) 56000 (b) 5600 (c) 560
  19. 19.Best estimate of 86 × 39? (a) 36000 (b) 3600 (c) 360
  20. 20.Best estimate of 82 × 16? (a) 160 (b) 16000 (c) 1600
  21. 21.Best estimate of 207 + 334? (a) 700 (b) 500 (c) 300
  22. 22.Best estimate of 409 + 424? (a) 1000 (b) 600 (c) 800
  23. 23.Best estimate of 648 + 225? (a) 600 (b) 800 (c) 1000
  24. 24.Best estimate of 473 + 287? (a) 1000 (b) 800 (c) 600
  25. 25.Best estimate of 21 × 52? (a) 10000 (b) 1000 (c) 100
  26. 26.Best estimate of 27 × 76? (a) 2400 (b) 24000 (c) 240
  27. 27.Best estimate of 34 × 63? (a) 18000 (b) 1800 (c) 180
  28. 28.Best estimate of 390 + 259? (a) 700 (b) 900 (c) 500
  29. 29.Best estimate of 26 × 76? (a) 2400 (b) 240 (c) 24000
  30. 30.Best estimate of 378 + 146? (a) 700 (b) 500 (c) 300
  31. 31.Best estimate of 29 × 56? (a) 18000 (b) 1800 (c) 180
  32. 32.Best estimate of 36 × 13? (a) 40 (b) 4000 (c) 400
  33. 33.Best estimate of 29 × 83? (a) 24000 (b) 2400 (c) 240
  34. 34.Best estimate of 19 × 68? (a) 1400 (b) 140 (c) 14000
  35. 35.Best estimate of 16 × 31? (a) 600 (b) 60 (c) 6000
  36. 36.Best estimate of 67 × 16? (a) 140 (b) 1400 (c) 14000
  37. 37.Best estimate of 586 + 179? (a) 600 (b) 800 (c) 1000
  38. 38.Best estimate of 171 + 189? (a) 400 (b) 600 (c) 200
  39. 39.Best estimate of 460 + 839? (a) 1300 (b) 1100 (c) 1500
  40. 40.Best estimate of 50 × 67? (a) 3500 (b) 350 (c) 35000

Answer key

  1. 1200
  2. 1800
  3. 600
  4. 500
  5. 5600
  6. 900
  7. 10000
  8. 3600
  9. 1500
  10. 3000
  11. 700
  12. 600
  13. 900
  14. 2500
  15. 1600
  16. 5400
  17. 600
  18. 5600
  19. 3600
  20. 1600
  21. 500
  22. 800
  23. 800
  24. 800
  25. 1000
  26. 2400
  27. 1800
  28. 700
  29. 2400
  30. 500
  31. 1800
  32. 400
  33. 2400
  34. 1400
  35. 600
  36. 1400
  37. 800
  38. 400
  39. 1300
  40. 3500

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