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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 725 · 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 61 × 22? (a) 12000 (b) 120 (c) 1200
  2. 2.Best estimate of 71 × 24? (a) 140 (b) 1400 (c) 14000
  3. 3.Best estimate of 51 × 13? (a) 500 (b) 5000 (c) 50
  4. 4.Best estimate of 28 × 19? (a) 6000 (b) 600 (c) 60
  5. 5.Best estimate of 56 × 57? (a) 36000 (b) 3600 (c) 360
  6. 6.Best estimate of 56 × 87? (a) 54000 (b) 540 (c) 5400
  7. 7.Best estimate of 442 + 189? (a) 800 (b) 600 (c) 400
  8. 8.Best estimate of 86 × 74? (a) 630 (b) 63000 (c) 6300
  9. 9.Best estimate of 816 + 207? (a) 800 (b) 1000 (c) 1200
  10. 10.Best estimate of 346 + 571? (a) 900 (b) 700 (c) 1100
  11. 11.Best estimate of 19 × 76? (a) 160 (b) 1600 (c) 16000
  12. 12.Best estimate of 146 + 374? (a) 700 (b) 300 (c) 500
  13. 13.Best estimate of 76 × 27? (a) 240 (b) 2400 (c) 24000
  14. 14.Best estimate of 98 × 87? (a) 900 (b) 90000 (c) 9000
  15. 15.Best estimate of 30 × 37? (a) 120 (b) 12000 (c) 1200
  16. 16.Best estimate of 339 + 416? (a) 900 (b) 700 (c) 500
  17. 17.Best estimate of 50 × 86? (a) 4500 (b) 45000 (c) 450
  18. 18.Best estimate of 78 × 16? (a) 1600 (b) 16000 (c) 160
  19. 19.Best estimate of 50 × 56? (a) 30000 (b) 300 (c) 3000
  20. 20.Best estimate of 351 + 367? (a) 600 (b) 800 (c) 1000
  21. 21.Best estimate of 60 × 92? (a) 5400 (b) 540 (c) 54000
  22. 22.Best estimate of 46 × 64? (a) 3000 (b) 300 (c) 30000
  23. 23.Best estimate of 817 + 443? (a) 1000 (b) 1400 (c) 1200
  24. 24.Best estimate of 838 + 778? (a) 1400 (b) 1800 (c) 1600
  25. 25.Best estimate of 771 + 461? (a) 1300 (b) 1100 (c) 1500
  26. 26.Best estimate of 96 × 22? (a) 2000 (b) 20000 (c) 200
  27. 27.Best estimate of 81 × 22? (a) 16000 (b) 1600 (c) 160
  28. 28.Best estimate of 766 + 402? (a) 1200 (b) 1400 (c) 1000
  29. 29.Best estimate of 37 × 56? (a) 240 (b) 24000 (c) 2400
  30. 30.Best estimate of 64 × 36? (a) 24000 (b) 240 (c) 2400
  31. 31.Best estimate of 91 × 54? (a) 4500 (b) 45000 (c) 450
  32. 32.Best estimate of 33 × 91? (a) 270 (b) 2700 (c) 27000
  33. 33.Best estimate of 13 × 24? (a) 2000 (b) 200 (c) 20
  34. 34.Best estimate of 347 + 729? (a) 1000 (b) 1200 (c) 800
  35. 35.Best estimate of 680 + 434? (a) 900 (b) 1300 (c) 1100
  36. 36.Best estimate of 62 × 73? (a) 4200 (b) 420 (c) 42000
  37. 37.Best estimate of 299 + 318? (a) 800 (b) 600 (c) 400
  38. 38.Best estimate of 200 + 751? (a) 1200 (b) 800 (c) 1000
  39. 39.Best estimate of 46 × 90? (a) 4500 (b) 450 (c) 45000
  40. 40.Best estimate of 877 + 778? (a) 1900 (b) 1700 (c) 1500

Answer key

  1. 1200
  2. 1400
  3. 500
  4. 600
  5. 3600
  6. 5400
  7. 600
  8. 6300
  9. 1000
  10. 900
  11. 1600
  12. 500
  13. 2400
  14. 9000
  15. 1200
  16. 700
  17. 4500
  18. 1600
  19. 3000
  20. 800
  21. 5400
  22. 3000
  23. 1200
  24. 1600
  25. 1300
  26. 2000
  27. 1600
  28. 1200
  29. 2400
  30. 2400
  31. 4500
  32. 2700
  33. 200
  34. 1000
  35. 1100
  36. 4200
  37. 600
  38. 1000
  39. 4500
  40. 1700

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