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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 194 · 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 71 × 82? (a) 560 (b) 56000 (c) 5600
  2. 2.Best estimate of 71 × 71? (a) 490 (b) 4900 (c) 49000
  3. 3.Best estimate of 205 + 829? (a) 1000 (b) 1200 (c) 800
  4. 4.Best estimate of 394 + 398? (a) 800 (b) 600 (c) 1000
  5. 5.Best estimate of 471 + 398? (a) 700 (b) 1100 (c) 900
  6. 6.Best estimate of 72 × 40? (a) 28000 (b) 280 (c) 2800
  7. 7.Best estimate of 42 × 52? (a) 20000 (b) 2000 (c) 200
  8. 8.Best estimate of 86 × 23? (a) 1800 (b) 18000 (c) 180
  9. 9.Best estimate of 472 + 387? (a) 1100 (b) 700 (c) 900
  10. 10.Best estimate of 309 + 395? (a) 900 (b) 500 (c) 700
  11. 11.Best estimate of 61 × 12? (a) 60 (b) 600 (c) 6000
  12. 12.Best estimate of 802 + 847? (a) 1600 (b) 1800 (c) 1400
  13. 13.Best estimate of 751 + 646? (a) 1400 (b) 1200 (c) 1600
  14. 14.Best estimate of 51 × 77? (a) 40000 (b) 4000 (c) 400
  15. 15.Best estimate of 392 + 549? (a) 1100 (b) 900 (c) 700
  16. 16.Best estimate of 26 × 21? (a) 60 (b) 6000 (c) 600
  17. 17.Best estimate of 160 + 123? (a) 100 (b) 300 (c) 500
  18. 18.Best estimate of 631 + 265? (a) 900 (b) 1100 (c) 700
  19. 19.Best estimate of 331 + 242? (a) 300 (b) 500 (c) 700
  20. 20.Best estimate of 82 × 29? (a) 24000 (b) 2400 (c) 240
  21. 21.Best estimate of 68 × 63? (a) 42000 (b) 420 (c) 4200
  22. 22.Best estimate of 56 × 61? (a) 36000 (b) 3600 (c) 360
  23. 23.Best estimate of 164 + 747? (a) 900 (b) 1100 (c) 700
  24. 24.Best estimate of 317 + 767? (a) 1100 (b) 900 (c) 1300
  25. 25.Best estimate of 805 + 662? (a) 1500 (b) 1700 (c) 1300
  26. 26.Best estimate of 209 + 489? (a) 700 (b) 500 (c) 900
  27. 27.Best estimate of 875 + 528? (a) 1200 (b) 1400 (c) 1600
  28. 28.Best estimate of 26 × 31? (a) 9000 (b) 900 (c) 90
  29. 29.Best estimate of 476 + 145? (a) 600 (b) 800 (c) 400
  30. 30.Best estimate of 97 × 86? (a) 90000 (b) 9000 (c) 900
  31. 31.Best estimate of 19 × 17? (a) 4000 (b) 400 (c) 40
  32. 32.Best estimate of 679 + 288? (a) 800 (b) 1200 (c) 1000
  33. 33.Best estimate of 74 × 52? (a) 3500 (b) 35000 (c) 350
  34. 34.Best estimate of 91 × 84? (a) 72000 (b) 7200 (c) 720
  35. 35.Best estimate of 476 + 780? (a) 1100 (b) 1500 (c) 1300
  36. 36.Best estimate of 790 + 327? (a) 1100 (b) 900 (c) 1300
  37. 37.Best estimate of 225 + 816? (a) 1200 (b) 800 (c) 1000
  38. 38.Best estimate of 357 + 240? (a) 600 (b) 800 (c) 400
  39. 39.Best estimate of 703 + 514? (a) 1000 (b) 1400 (c) 1200
  40. 40.Best estimate of 235 + 474? (a) 700 (b) 900 (c) 500

Answer key

  1. 5600
  2. 4900
  3. 1000
  4. 800
  5. 900
  6. 2800
  7. 2000
  8. 1800
  9. 900
  10. 700
  11. 600
  12. 1600
  13. 1400
  14. 4000
  15. 900
  16. 600
  17. 300
  18. 900
  19. 500
  20. 2400
  21. 4200
  22. 3600
  23. 900
  24. 1100
  25. 1500
  26. 700
  27. 1400
  28. 900
  29. 600
  30. 9000
  31. 400
  32. 1000
  33. 3500
  34. 7200
  35. 1300
  36. 1100
  37. 1000
  38. 600
  39. 1200
  40. 700

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