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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 311 · 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 247 + 878? (a) 900 (b) 1300 (c) 1100
  2. 2.Best estimate of 355 + 216? (a) 400 (b) 800 (c) 600
  3. 3.Best estimate of 804 + 670? (a) 1700 (b) 1300 (c) 1500
  4. 4.Best estimate of 21 × 66? (a) 1400 (b) 140 (c) 14000
  5. 5.Best estimate of 206 + 232? (a) 400 (b) 600 (c) 200
  6. 6.Best estimate of 407 + 205? (a) 400 (b) 800 (c) 600
  7. 7.Best estimate of 146 + 533? (a) 400 (b) 600 (c) 800
  8. 8.Best estimate of 463 + 639? (a) 900 (b) 1300 (c) 1100
  9. 9.Best estimate of 808 + 631? (a) 1600 (b) 1200 (c) 1400
  10. 10.Best estimate of 18 × 42? (a) 8000 (b) 800 (c) 80
  11. 11.Best estimate of 97 × 96? (a) 10000 (b) 100000 (c) 1000
  12. 12.Best estimate of 73 × 37? (a) 28000 (b) 280 (c) 2800
  13. 13.Best estimate of 19 × 71? (a) 140 (b) 14000 (c) 1400
  14. 14.Best estimate of 364 + 590? (a) 1000 (b) 1200 (c) 800
  15. 15.Best estimate of 515 + 541? (a) 1000 (b) 1200 (c) 800
  16. 16.Best estimate of 62 × 17? (a) 12000 (b) 1200 (c) 120
  17. 17.Best estimate of 14 × 18? (a) 200 (b) 2000 (c) 20
  18. 18.Best estimate of 44 × 59? (a) 240 (b) 2400 (c) 24000
  19. 19.Best estimate of 226 + 602? (a) 600 (b) 800 (c) 1000
  20. 20.Best estimate of 46 × 67? (a) 35000 (b) 3500 (c) 350
  21. 21.Best estimate of 42 × 32? (a) 12000 (b) 120 (c) 1200
  22. 22.Best estimate of 37 × 16? (a) 800 (b) 80 (c) 8000
  23. 23.Best estimate of 27 × 69? (a) 2100 (b) 21000 (c) 210
  24. 24.Best estimate of 773 + 618? (a) 1600 (b) 1400 (c) 1200
  25. 25.Best estimate of 639 + 799? (a) 1200 (b) 1400 (c) 1600
  26. 26.Best estimate of 729 + 821? (a) 1700 (b) 1300 (c) 1500
  27. 27.Best estimate of 304 + 582? (a) 1100 (b) 700 (c) 900
  28. 28.Best estimate of 751 + 581? (a) 1400 (b) 1200 (c) 1600
  29. 29.Best estimate of 79 × 77? (a) 640 (b) 6400 (c) 64000
  30. 30.Best estimate of 72 × 88? (a) 6300 (b) 630 (c) 63000
  31. 31.Best estimate of 26 × 86? (a) 27000 (b) 270 (c) 2700
  32. 32.Best estimate of 338 + 743? (a) 1000 (b) 1200 (c) 800
  33. 33.Best estimate of 608 + 801? (a) 1400 (b) 1600 (c) 1200
  34. 34.Best estimate of 41 × 28? (a) 1200 (b) 120 (c) 12000
  35. 35.Best estimate of 703 + 849? (a) 1500 (b) 1300 (c) 1700
  36. 36.Best estimate of 62 × 66? (a) 4200 (b) 420 (c) 42000
  37. 37.Best estimate of 88 × 36? (a) 360 (b) 36000 (c) 3600
  38. 38.Best estimate of 13 × 22? (a) 2000 (b) 20 (c) 200
  39. 39.Best estimate of 415 + 458? (a) 700 (b) 1100 (c) 900
  40. 40.Best estimate of 209 + 166? (a) 400 (b) 200 (c) 600

Answer key

  1. 1100
  2. 600
  3. 1500
  4. 1400
  5. 400
  6. 600
  7. 600
  8. 1100
  9. 1400
  10. 800
  11. 10000
  12. 2800
  13. 1400
  14. 1000
  15. 1000
  16. 1200
  17. 200
  18. 2400
  19. 800
  20. 3500
  21. 1200
  22. 800
  23. 2100
  24. 1400
  25. 1400
  26. 1500
  27. 900
  28. 1400
  29. 6400
  30. 6300
  31. 2700
  32. 1000
  33. 1400
  34. 1200
  35. 1500
  36. 4200
  37. 3600
  38. 200
  39. 900
  40. 400

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