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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 578 · 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 262 + 126? (a) 600 (b) 400 (c) 200
  2. 2.Best estimate of 73 × 28? (a) 210 (b) 2100 (c) 21000
  3. 3.Best estimate of 420 + 803? (a) 1000 (b) 1200 (c) 1400
  4. 4.Best estimate of 57 × 29? (a) 1800 (b) 180 (c) 18000
  5. 5.Best estimate of 69 × 86? (a) 63000 (b) 630 (c) 6300
  6. 6.Best estimate of 80 × 16? (a) 1600 (b) 16000 (c) 160
  7. 7.Best estimate of 454 + 235? (a) 500 (b) 700 (c) 900
  8. 8.Best estimate of 535 + 418? (a) 700 (b) 1100 (c) 900
  9. 9.Best estimate of 334 + 641? (a) 900 (b) 1100 (c) 700
  10. 10.Best estimate of 184 + 465? (a) 700 (b) 500 (c) 900
  11. 11.Best estimate of 39 × 36? (a) 160 (b) 1600 (c) 16000
  12. 12.Best estimate of 82 × 29? (a) 2400 (b) 240 (c) 24000
  13. 13.Best estimate of 72 × 98? (a) 7000 (b) 700 (c) 70000
  14. 14.Best estimate of 49 × 30? (a) 15000 (b) 150 (c) 1500
  15. 15.Best estimate of 826 + 474? (a) 1500 (b) 1100 (c) 1300
  16. 16.Best estimate of 171 + 713? (a) 900 (b) 700 (c) 1100
  17. 17.Best estimate of 29 × 46? (a) 15000 (b) 150 (c) 1500
  18. 18.Best estimate of 58 × 74? (a) 4200 (b) 420 (c) 42000
  19. 19.Best estimate of 281 + 206? (a) 500 (b) 700 (c) 300
  20. 20.Best estimate of 16 × 28? (a) 6000 (b) 60 (c) 600
  21. 21.Best estimate of 162 + 403? (a) 400 (b) 600 (c) 800
  22. 22.Best estimate of 26 × 77? (a) 2400 (b) 240 (c) 24000
  23. 23.Best estimate of 589 + 165? (a) 800 (b) 1000 (c) 600
  24. 24.Best estimate of 379 + 877? (a) 1100 (b) 1500 (c) 1300
  25. 25.Best estimate of 509 + 411? (a) 900 (b) 700 (c) 1100
  26. 26.Best estimate of 57 × 54? (a) 300 (b) 30000 (c) 3000
  27. 27.Best estimate of 515 + 816? (a) 1100 (b) 1500 (c) 1300
  28. 28.Best estimate of 21 × 39? (a) 8000 (b) 800 (c) 80
  29. 29.Best estimate of 56 × 48? (a) 30000 (b) 300 (c) 3000
  30. 30.Best estimate of 239 + 584? (a) 800 (b) 600 (c) 1000
  31. 31.Best estimate of 31 × 46? (a) 150 (b) 1500 (c) 15000
  32. 32.Best estimate of 138 + 480? (a) 800 (b) 400 (c) 600
  33. 33.Best estimate of 28 × 70? (a) 210 (b) 2100 (c) 21000
  34. 34.Best estimate of 246 + 779? (a) 1200 (b) 800 (c) 1000
  35. 35.Best estimate of 799 + 803? (a) 1800 (b) 1600 (c) 1400
  36. 36.Best estimate of 37 × 73? (a) 2800 (b) 280 (c) 28000
  37. 37.Best estimate of 44 × 28? (a) 120 (b) 1200 (c) 12000
  38. 38.Best estimate of 82 × 16? (a) 160 (b) 1600 (c) 16000
  39. 39.Best estimate of 91 × 61? (a) 5400 (b) 540 (c) 54000
  40. 40.Best estimate of 94 × 22? (a) 1800 (b) 180 (c) 18000

Answer key

  1. 400
  2. 2100
  3. 1200
  4. 1800
  5. 6300
  6. 1600
  7. 700
  8. 900
  9. 900
  10. 700
  11. 1600
  12. 2400
  13. 7000
  14. 1500
  15. 1300
  16. 900
  17. 1500
  18. 4200
  19. 500
  20. 600
  21. 600
  22. 2400
  23. 800
  24. 1300
  25. 900
  26. 3000
  27. 1300
  28. 800
  29. 3000
  30. 800
  31. 1500
  32. 600
  33. 2100
  34. 1000
  35. 1600
  36. 2800
  37. 1200
  38. 1600
  39. 5400
  40. 1800

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