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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 179 · 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 540 + 313? (a) 600 (b) 1000 (c) 800
  2. 2.Best estimate of 53 × 62? (a) 3000 (b) 30000 (c) 300
  3. 3.Best estimate of 21 × 77? (a) 1600 (b) 16000 (c) 160
  4. 4.Best estimate of 16 × 24? (a) 40 (b) 400 (c) 4000
  5. 5.Best estimate of 154 + 620? (a) 600 (b) 1000 (c) 800
  6. 6.Best estimate of 38 × 76? (a) 32000 (b) 320 (c) 3200
  7. 7.Best estimate of 26 × 70? (a) 2100 (b) 21000 (c) 210
  8. 8.Best estimate of 97 × 54? (a) 5000 (b) 500 (c) 50000
  9. 9.Best estimate of 97 × 16? (a) 200 (b) 20000 (c) 2000
  10. 10.Best estimate of 212 + 354? (a) 600 (b) 800 (c) 400
  11. 11.Best estimate of 688 + 213? (a) 900 (b) 700 (c) 1100
  12. 12.Best estimate of 60 × 61? (a) 3600 (b) 360 (c) 36000
  13. 13.Best estimate of 76 × 88? (a) 7200 (b) 720 (c) 72000
  14. 14.Best estimate of 88 × 46? (a) 4500 (b) 450 (c) 45000
  15. 15.Best estimate of 368 + 590? (a) 1000 (b) 1200 (c) 800
  16. 16.Best estimate of 60 × 41? (a) 24000 (b) 240 (c) 2400
  17. 17.Best estimate of 712 + 285? (a) 800 (b) 1200 (c) 1000
  18. 18.Best estimate of 30 × 97? (a) 30000 (b) 3000 (c) 300
  19. 19.Best estimate of 648 + 721? (a) 1300 (b) 1500 (c) 1100
  20. 20.Best estimate of 23 × 16? (a) 400 (b) 4000 (c) 40
  21. 21.Best estimate of 48 × 66? (a) 350 (b) 3500 (c) 35000
  22. 22.Best estimate of 47 × 68? (a) 3500 (b) 350 (c) 35000
  23. 23.Best estimate of 520 + 449? (a) 1100 (b) 900 (c) 700
  24. 24.Best estimate of 346 + 626? (a) 900 (b) 700 (c) 1100
  25. 25.Best estimate of 36 × 61? (a) 2400 (b) 240 (c) 24000
  26. 26.Best estimate of 16 × 21? (a) 4000 (b) 40 (c) 400
  27. 27.Best estimate of 222 + 149? (a) 100 (b) 500 (c) 300
  28. 28.Best estimate of 23 × 54? (a) 100 (b) 1000 (c) 10000
  29. 29.Best estimate of 481 + 477? (a) 1200 (b) 1000 (c) 800
  30. 30.Best estimate of 56 × 93? (a) 54000 (b) 5400 (c) 540
  31. 31.Best estimate of 501 + 303? (a) 1000 (b) 600 (c) 800
  32. 32.Best estimate of 23 × 61? (a) 12000 (b) 120 (c) 1200
  33. 33.Best estimate of 76 × 62? (a) 48000 (b) 4800 (c) 480
  34. 34.Best estimate of 66 × 17? (a) 1400 (b) 14000 (c) 140
  35. 35.Best estimate of 489 + 609? (a) 1100 (b) 1300 (c) 900
  36. 36.Best estimate of 61 × 52? (a) 3000 (b) 30000 (c) 300
  37. 37.Best estimate of 54 × 13? (a) 500 (b) 5000 (c) 50
  38. 38.Best estimate of 198 + 742? (a) 900 (b) 700 (c) 1100
  39. 39.Best estimate of 548 + 165? (a) 900 (b) 700 (c) 500
  40. 40.Best estimate of 360 + 289? (a) 900 (b) 500 (c) 700

Answer key

  1. 800
  2. 3000
  3. 1600
  4. 400
  5. 800
  6. 3200
  7. 2100
  8. 5000
  9. 2000
  10. 600
  11. 900
  12. 3600
  13. 7200
  14. 4500
  15. 1000
  16. 2400
  17. 1000
  18. 3000
  19. 1300
  20. 400
  21. 3500
  22. 3500
  23. 900
  24. 900
  25. 2400
  26. 400
  27. 300
  28. 1000
  29. 1000
  30. 5400
  31. 800
  32. 1200
  33. 4800
  34. 1400
  35. 1100
  36. 3000
  37. 500
  38. 900
  39. 700
  40. 700

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