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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 261 · 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 326 + 821? (a) 1300 (b) 1100 (c) 900
  2. 2.Best estimate of 790 + 351? (a) 1200 (b) 1000 (c) 1400
  3. 3.Best estimate of 168 + 719? (a) 900 (b) 1100 (c) 700
  4. 4.Best estimate of 47 × 94? (a) 450 (b) 4500 (c) 45000
  5. 5.Best estimate of 32 × 69? (a) 2100 (b) 21000 (c) 210
  6. 6.Best estimate of 33 × 66? (a) 2100 (b) 21000 (c) 210
  7. 7.Best estimate of 61 × 44? (a) 2400 (b) 240 (c) 24000
  8. 8.Best estimate of 30 × 12? (a) 3000 (b) 30 (c) 300
  9. 9.Best estimate of 39 × 41? (a) 160 (b) 16000 (c) 1600
  10. 10.Best estimate of 94 × 50? (a) 450 (b) 4500 (c) 45000
  11. 11.Best estimate of 588 + 127? (a) 500 (b) 700 (c) 900
  12. 12.Best estimate of 38 × 16? (a) 8000 (b) 80 (c) 800
  13. 13.Best estimate of 252 + 509? (a) 800 (b) 600 (c) 1000
  14. 14.Best estimate of 519 + 864? (a) 1600 (b) 1400 (c) 1200
  15. 15.Best estimate of 202 + 256? (a) 700 (b) 300 (c) 500
  16. 16.Best estimate of 98 × 18? (a) 200 (b) 20000 (c) 2000
  17. 17.Best estimate of 96 × 64? (a) 6000 (b) 60000 (c) 600
  18. 18.Best estimate of 36 × 39? (a) 1600 (b) 16000 (c) 160
  19. 19.Best estimate of 16 × 24? (a) 400 (b) 40 (c) 4000
  20. 20.Best estimate of 47 × 40? (a) 2000 (b) 200 (c) 20000
  21. 21.Best estimate of 26 × 50? (a) 15000 (b) 1500 (c) 150
  22. 22.Best estimate of 19 × 39? (a) 8000 (b) 80 (c) 800
  23. 23.Best estimate of 66 × 42? (a) 280 (b) 28000 (c) 2800
  24. 24.Best estimate of 603 + 542? (a) 1300 (b) 1100 (c) 900
  25. 25.Best estimate of 77 × 90? (a) 720 (b) 7200 (c) 72000
  26. 26.Best estimate of 20 × 13? (a) 2000 (b) 200 (c) 20
  27. 27.Best estimate of 691 + 861? (a) 1400 (b) 1800 (c) 1600
  28. 28.Best estimate of 56 × 59? (a) 3600 (b) 360 (c) 36000
  29. 29.Best estimate of 764 + 701? (a) 1700 (b) 1500 (c) 1300
  30. 30.Best estimate of 185 + 691? (a) 700 (b) 900 (c) 1100
  31. 31.Best estimate of 522 + 181? (a) 700 (b) 500 (c) 900
  32. 32.Best estimate of 769 + 351? (a) 1400 (b) 1200 (c) 1000
  33. 33.Best estimate of 16 × 60? (a) 12000 (b) 1200 (c) 120
  34. 34.Best estimate of 87 × 19? (a) 1800 (b) 18000 (c) 180
  35. 35.Best estimate of 48 × 88? (a) 4500 (b) 45000 (c) 450
  36. 36.Best estimate of 435 + 584? (a) 1000 (b) 1200 (c) 800
  37. 37.Best estimate of 363 + 166? (a) 600 (b) 800 (c) 400
  38. 38.Best estimate of 26 × 31? (a) 90 (b) 900 (c) 9000
  39. 39.Best estimate of 694 + 184? (a) 700 (b) 900 (c) 1100
  40. 40.Best estimate of 289 + 568? (a) 1100 (b) 700 (c) 900

Answer key

  1. 1100
  2. 1200
  3. 900
  4. 4500
  5. 2100
  6. 2100
  7. 2400
  8. 300
  9. 1600
  10. 4500
  11. 700
  12. 800
  13. 800
  14. 1400
  15. 500
  16. 2000
  17. 6000
  18. 1600
  19. 400
  20. 2000
  21. 1500
  22. 800
  23. 2800
  24. 1100
  25. 7200
  26. 200
  27. 1600
  28. 3600
  29. 1500
  30. 900
  31. 700
  32. 1200
  33. 1200
  34. 1800
  35. 4500
  36. 1000
  37. 600
  38. 900
  39. 900
  40. 900

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