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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 896 · 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 305 + 544? (a) 1000 (b) 600 (c) 800
  2. 2.Best estimate of 88 × 26? (a) 2700 (b) 270 (c) 27000
  3. 3.Best estimate of 69 × 59? (a) 420 (b) 4200 (c) 42000
  4. 4.Best estimate of 94 × 47? (a) 45000 (b) 4500 (c) 450
  5. 5.Best estimate of 50 × 43? (a) 2000 (b) 200 (c) 20000
  6. 6.Best estimate of 202 + 271? (a) 700 (b) 300 (c) 500
  7. 7.Best estimate of 32 × 76? (a) 240 (b) 24000 (c) 2400
  8. 8.Best estimate of 37 × 38? (a) 1600 (b) 16000 (c) 160
  9. 9.Best estimate of 372 + 216? (a) 800 (b) 600 (c) 400
  10. 10.Best estimate of 18 × 36? (a) 80 (b) 800 (c) 8000
  11. 11.Best estimate of 24 × 14? (a) 20 (b) 2000 (c) 200
  12. 12.Best estimate of 487 + 484? (a) 800 (b) 1000 (c) 1200
  13. 13.Best estimate of 51 × 91? (a) 45000 (b) 450 (c) 4500
  14. 14.Best estimate of 79 × 82? (a) 64000 (b) 640 (c) 6400
  15. 15.Best estimate of 63 × 71? (a) 4200 (b) 42000 (c) 420
  16. 16.Best estimate of 23 × 34? (a) 60 (b) 6000 (c) 600
  17. 17.Best estimate of 29 × 22? (a) 60 (b) 6000 (c) 600
  18. 18.Best estimate of 640 + 506? (a) 1100 (b) 1300 (c) 900
  19. 19.Best estimate of 233 + 587? (a) 600 (b) 1000 (c) 800
  20. 20.Best estimate of 92 × 22? (a) 18000 (b) 1800 (c) 180
  21. 21.Best estimate of 606 + 362? (a) 1200 (b) 1000 (c) 800
  22. 22.Best estimate of 37 × 37? (a) 16000 (b) 1600 (c) 160
  23. 23.Best estimate of 492 + 344? (a) 800 (b) 600 (c) 1000
  24. 24.Best estimate of 84 × 88? (a) 720 (b) 7200 (c) 72000
  25. 25.Best estimate of 221 + 151? (a) 600 (b) 400 (c) 200
  26. 26.Best estimate of 44 × 16? (a) 800 (b) 80 (c) 8000
  27. 27.Best estimate of 181 + 435? (a) 800 (b) 600 (c) 400
  28. 28.Best estimate of 70 × 57? (a) 420 (b) 42000 (c) 4200
  29. 29.Best estimate of 684 + 248? (a) 900 (b) 1100 (c) 700
  30. 30.Best estimate of 32 × 17? (a) 6000 (b) 60 (c) 600
  31. 31.Best estimate of 668 + 579? (a) 1500 (b) 1100 (c) 1300
  32. 32.Best estimate of 789 + 252? (a) 900 (b) 1300 (c) 1100
  33. 33.Best estimate of 488 + 558? (a) 1100 (b) 1300 (c) 900
  34. 34.Best estimate of 811 + 590? (a) 1400 (b) 1200 (c) 1600
  35. 35.Best estimate of 86 × 46? (a) 450 (b) 45000 (c) 4500
  36. 36.Best estimate of 701 + 189? (a) 900 (b) 700 (c) 1100
  37. 37.Best estimate of 695 + 661? (a) 1400 (b) 1200 (c) 1600
  38. 38.Best estimate of 78 × 21? (a) 1600 (b) 16000 (c) 160
  39. 39.Best estimate of 548 + 177? (a) 700 (b) 900 (c) 500
  40. 40.Best estimate of 848 + 751? (a) 1600 (b) 1400 (c) 1800

Answer key

  1. 800
  2. 2700
  3. 4200
  4. 4500
  5. 2000
  6. 500
  7. 2400
  8. 1600
  9. 600
  10. 800
  11. 200
  12. 1000
  13. 4500
  14. 6400
  15. 4200
  16. 600
  17. 600
  18. 1100
  19. 800
  20. 1800
  21. 1000
  22. 1600
  23. 800
  24. 7200
  25. 400
  26. 800
  27. 600
  28. 4200
  29. 900
  30. 600
  31. 1300
  32. 1100
  33. 1100
  34. 1400
  35. 4500
  36. 900
  37. 1400
  38. 1600
  39. 700
  40. 1600

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