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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 909 · 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 169 + 127? (a) 500 (b) 100 (c) 300
  2. 2.Best estimate of 576 + 727? (a) 1300 (b) 1100 (c) 1500
  3. 3.Best estimate of 473 + 348? (a) 600 (b) 1000 (c) 800
  4. 4.Best estimate of 91 × 30? (a) 27000 (b) 2700 (c) 270
  5. 5.Best estimate of 21 × 38? (a) 800 (b) 8000 (c) 80
  6. 6.Best estimate of 238 + 408? (a) 400 (b) 600 (c) 800
  7. 7.Best estimate of 554 + 777? (a) 1200 (b) 1400 (c) 1600
  8. 8.Best estimate of 712 + 294? (a) 800 (b) 1000 (c) 1200
  9. 9.Best estimate of 33 × 52? (a) 1500 (b) 150 (c) 15000
  10. 10.Best estimate of 583 + 617? (a) 1000 (b) 1200 (c) 1400
  11. 11.Best estimate of 97 × 59? (a) 600 (b) 6000 (c) 60000
  12. 12.Best estimate of 310 + 655? (a) 1200 (b) 800 (c) 1000
  13. 13.Best estimate of 251 + 220? (a) 500 (b) 700 (c) 300
  14. 14.Best estimate of 751 + 352? (a) 1000 (b) 1400 (c) 1200
  15. 15.Best estimate of 73 × 43? (a) 28000 (b) 2800 (c) 280
  16. 16.Best estimate of 322 + 214? (a) 500 (b) 700 (c) 300
  17. 17.Best estimate of 21 × 91? (a) 180 (b) 1800 (c) 18000
  18. 18.Best estimate of 93 × 31? (a) 270 (b) 27000 (c) 2700
  19. 19.Best estimate of 64 × 37? (a) 24000 (b) 240 (c) 2400
  20. 20.Best estimate of 657 + 823? (a) 1500 (b) 1300 (c) 1700
  21. 21.Best estimate of 526 + 855? (a) 1400 (b) 1600 (c) 1200
  22. 22.Best estimate of 96 × 46? (a) 50000 (b) 500 (c) 5000
  23. 23.Best estimate of 44 × 21? (a) 8000 (b) 800 (c) 80
  24. 24.Best estimate of 559 + 481? (a) 1300 (b) 1100 (c) 900
  25. 25.Best estimate of 734 + 780? (a) 1500 (b) 1300 (c) 1700
  26. 26.Best estimate of 80 × 28? (a) 24000 (b) 240 (c) 2400
  27. 27.Best estimate of 38 × 90? (a) 360 (b) 36000 (c) 3600
  28. 28.Best estimate of 12 × 13? (a) 100 (b) 1000 (c) 10
  29. 29.Best estimate of 219 + 266? (a) 700 (b) 300 (c) 500
  30. 30.Best estimate of 26 × 37? (a) 120 (b) 12000 (c) 1200
  31. 31.Best estimate of 76 × 22? (a) 160 (b) 16000 (c) 1600
  32. 32.Best estimate of 379 + 710? (a) 900 (b) 1300 (c) 1100
  33. 33.Best estimate of 94 × 96? (a) 900 (b) 90000 (c) 9000
  34. 34.Best estimate of 519 + 842? (a) 1500 (b) 1300 (c) 1100
  35. 35.Best estimate of 82 × 53? (a) 4000 (b) 40000 (c) 400
  36. 36.Best estimate of 20 × 96? (a) 20000 (b) 2000 (c) 200
  37. 37.Best estimate of 42 × 96? (a) 40000 (b) 4000 (c) 400
  38. 38.Best estimate of 630 + 615? (a) 1400 (b) 1000 (c) 1200
  39. 39.Best estimate of 48 × 13? (a) 500 (b) 5000 (c) 50
  40. 40.Best estimate of 851 + 287? (a) 1000 (b) 1200 (c) 1400

Answer key

  1. 300
  2. 1300
  3. 800
  4. 2700
  5. 800
  6. 600
  7. 1400
  8. 1000
  9. 1500
  10. 1200
  11. 6000
  12. 1000
  13. 500
  14. 1200
  15. 2800
  16. 500
  17. 1800
  18. 2700
  19. 2400
  20. 1500
  21. 1400
  22. 5000
  23. 800
  24. 1100
  25. 1500
  26. 2400
  27. 3600
  28. 100
  29. 500
  30. 1200
  31. 1600
  32. 1100
  33. 9000
  34. 1300
  35. 4000
  36. 2000
  37. 4000
  38. 1200
  39. 500
  40. 1200

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