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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 13 · 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 27 × 71? (a) 2100 (b) 210 (c) 21000
  2. 2.Best estimate of 514 + 790? (a) 1500 (b) 1100 (c) 1300
  3. 3.Best estimate of 861 + 454? (a) 1400 (b) 1600 (c) 1200
  4. 4.Best estimate of 36 × 47? (a) 2000 (b) 20000 (c) 200
  5. 5.Best estimate of 464 + 328? (a) 1000 (b) 600 (c) 800
  6. 6.Best estimate of 86 × 80? (a) 72000 (b) 7200 (c) 720
  7. 7.Best estimate of 68 × 66? (a) 490 (b) 49000 (c) 4900
  8. 8.Best estimate of 80 × 36? (a) 32000 (b) 3200 (c) 320
  9. 9.Best estimate of 26 × 54? (a) 15000 (b) 150 (c) 1500
  10. 10.Best estimate of 13 × 41? (a) 40 (b) 400 (c) 4000
  11. 11.Best estimate of 385 + 488? (a) 900 (b) 700 (c) 1100
  12. 12.Best estimate of 291 + 424? (a) 500 (b) 900 (c) 700
  13. 13.Best estimate of 73 × 13? (a) 7000 (b) 700 (c) 70
  14. 14.Best estimate of 74 × 46? (a) 35000 (b) 350 (c) 3500
  15. 15.Best estimate of 67 × 38? (a) 280 (b) 28000 (c) 2800
  16. 16.Best estimate of 513 + 425? (a) 1100 (b) 900 (c) 700
  17. 17.Best estimate of 96 × 36? (a) 40000 (b) 400 (c) 4000
  18. 18.Best estimate of 68 × 68? (a) 490 (b) 49000 (c) 4900
  19. 19.Best estimate of 267 + 285? (a) 800 (b) 600 (c) 400
  20. 20.Best estimate of 404 + 866? (a) 1300 (b) 1500 (c) 1100
  21. 21.Best estimate of 156 + 544? (a) 700 (b) 500 (c) 900
  22. 22.Best estimate of 51 × 28? (a) 1500 (b) 150 (c) 15000
  23. 23.Best estimate of 26 × 89? (a) 2700 (b) 27000 (c) 270
  24. 24.Best estimate of 349 + 307? (a) 800 (b) 600 (c) 400
  25. 25.Best estimate of 43 × 23? (a) 8000 (b) 80 (c) 800
  26. 26.Best estimate of 132 + 121? (a) 0 (b) 200 (c) 400
  27. 27.Best estimate of 741 + 361? (a) 1300 (b) 900 (c) 1100
  28. 28.Best estimate of 46 × 36? (a) 2000 (b) 200 (c) 20000
  29. 29.Best estimate of 701 + 864? (a) 1800 (b) 1400 (c) 1600
  30. 30.Best estimate of 76 × 46? (a) 40000 (b) 4000 (c) 400
  31. 31.Best estimate of 651 + 145? (a) 1000 (b) 800 (c) 600
  32. 32.Best estimate of 54 × 42? (a) 20000 (b) 2000 (c) 200
  33. 33.Best estimate of 577 + 203? (a) 800 (b) 1000 (c) 600
  34. 34.Best estimate of 16 × 82? (a) 160 (b) 1600 (c) 16000
  35. 35.Best estimate of 459 + 788? (a) 1300 (b) 1100 (c) 1500
  36. 36.Best estimate of 554 + 745? (a) 1300 (b) 1100 (c) 1500
  37. 37.Best estimate of 39 × 86? (a) 3600 (b) 36000 (c) 360
  38. 38.Best estimate of 19 × 76? (a) 160 (b) 16000 (c) 1600
  39. 39.Best estimate of 558 + 408? (a) 1000 (b) 1200 (c) 800
  40. 40.Best estimate of 17 × 13? (a) 20 (b) 2000 (c) 200

Answer key

  1. 2100
  2. 1300
  3. 1400
  4. 2000
  5. 800
  6. 7200
  7. 4900
  8. 3200
  9. 1500
  10. 400
  11. 900
  12. 700
  13. 700
  14. 3500
  15. 2800
  16. 900
  17. 4000
  18. 4900
  19. 600
  20. 1300
  21. 700
  22. 1500
  23. 2700
  24. 600
  25. 800
  26. 200
  27. 1100
  28. 2000
  29. 1600
  30. 4000
  31. 800
  32. 2000
  33. 800
  34. 1600
  35. 1300
  36. 1300
  37. 3600
  38. 1600
  39. 1000
  40. 200

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