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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 327 · 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 36 × 57? (a) 2400 (b) 240 (c) 24000
  2. 2.Best estimate of 24 × 46? (a) 10000 (b) 1000 (c) 100
  3. 3.Best estimate of 252 + 324? (a) 600 (b) 800 (c) 400
  4. 4.Best estimate of 92 × 24? (a) 180 (b) 1800 (c) 18000
  5. 5.Best estimate of 30 × 72? (a) 210 (b) 2100 (c) 21000
  6. 6.Best estimate of 125 + 142? (a) 400 (b) 0 (c) 200
  7. 7.Best estimate of 287 + 528? (a) 800 (b) 600 (c) 1000
  8. 8.Best estimate of 93 × 57? (a) 540 (b) 5400 (c) 54000
  9. 9.Best estimate of 26 × 43? (a) 120 (b) 12000 (c) 1200
  10. 10.Best estimate of 91 × 64? (a) 540 (b) 54000 (c) 5400
  11. 11.Best estimate of 88 × 67? (a) 63000 (b) 6300 (c) 630
  12. 12.Best estimate of 66 × 29? (a) 21000 (b) 2100 (c) 210
  13. 13.Best estimate of 62 × 93? (a) 5400 (b) 540 (c) 54000
  14. 14.Best estimate of 70 × 48? (a) 35000 (b) 350 (c) 3500
  15. 15.Best estimate of 280 + 836? (a) 900 (b) 1100 (c) 1300
  16. 16.Best estimate of 44 × 41? (a) 1600 (b) 16000 (c) 160
  17. 17.Best estimate of 14 × 34? (a) 3000 (b) 300 (c) 30
  18. 18.Best estimate of 820 + 789? (a) 1600 (b) 1400 (c) 1800
  19. 19.Best estimate of 367 + 534? (a) 700 (b) 900 (c) 1100
  20. 20.Best estimate of 856 + 434? (a) 1500 (b) 1300 (c) 1100
  21. 21.Best estimate of 662 + 484? (a) 1200 (b) 1000 (c) 1400
  22. 22.Best estimate of 61 × 64? (a) 360 (b) 3600 (c) 36000
  23. 23.Best estimate of 83 × 62? (a) 480 (b) 4800 (c) 48000
  24. 24.Best estimate of 24 × 54? (a) 1000 (b) 100 (c) 10000
  25. 25.Best estimate of 66 × 36? (a) 2800 (b) 28000 (c) 280
  26. 26.Best estimate of 73 × 21? (a) 140 (b) 1400 (c) 14000
  27. 27.Best estimate of 68 × 16? (a) 14000 (b) 1400 (c) 140
  28. 28.Best estimate of 341 + 220? (a) 300 (b) 500 (c) 700
  29. 29.Best estimate of 619 + 254? (a) 900 (b) 700 (c) 1100
  30. 30.Best estimate of 633 + 843? (a) 1600 (b) 1200 (c) 1400
  31. 31.Best estimate of 554 + 825? (a) 1400 (b) 1200 (c) 1600
  32. 32.Best estimate of 627 + 708? (a) 1100 (b) 1500 (c) 1300
  33. 33.Best estimate of 177 + 374? (a) 800 (b) 400 (c) 600
  34. 34.Best estimate of 420 + 344? (a) 700 (b) 500 (c) 900
  35. 35.Best estimate of 561 + 514? (a) 900 (b) 1100 (c) 1300
  36. 36.Best estimate of 97 × 16? (a) 20000 (b) 200 (c) 2000
  37. 37.Best estimate of 177 + 186? (a) 400 (b) 600 (c) 200
  38. 38.Best estimate of 412 + 524? (a) 1100 (b) 700 (c) 900
  39. 39.Best estimate of 648 + 431? (a) 800 (b) 1000 (c) 1200
  40. 40.Best estimate of 642 + 183? (a) 600 (b) 1000 (c) 800

Answer key

  1. 2400
  2. 1000
  3. 600
  4. 1800
  5. 2100
  6. 200
  7. 800
  8. 5400
  9. 1200
  10. 5400
  11. 6300
  12. 2100
  13. 5400
  14. 3500
  15. 1100
  16. 1600
  17. 300
  18. 1600
  19. 900
  20. 1300
  21. 1200
  22. 3600
  23. 4800
  24. 1000
  25. 2800
  26. 1400
  27. 1400
  28. 500
  29. 900
  30. 1400
  31. 1400
  32. 1300
  33. 600
  34. 700
  35. 1100
  36. 2000
  37. 400
  38. 900
  39. 1000
  40. 800

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