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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 575 · 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 38 × 14? (a) 400 (b) 4000 (c) 40
  2. 2.Best estimate of 169 + 272? (a) 700 (b) 300 (c) 500
  3. 3.Best estimate of 369 + 246? (a) 400 (b) 600 (c) 800
  4. 4.Best estimate of 246 + 396? (a) 600 (b) 400 (c) 800
  5. 5.Best estimate of 42 × 94? (a) 3600 (b) 36000 (c) 360
  6. 6.Best estimate of 74 × 69? (a) 49000 (b) 4900 (c) 490
  7. 7.Best estimate of 93 × 82? (a) 720 (b) 72000 (c) 7200
  8. 8.Best estimate of 76 × 70? (a) 56000 (b) 560 (c) 5600
  9. 9.Best estimate of 90 × 71? (a) 6300 (b) 63000 (c) 630
  10. 10.Best estimate of 28 × 74? (a) 2100 (b) 21000 (c) 210
  11. 11.Best estimate of 92 × 28? (a) 27000 (b) 270 (c) 2700
  12. 12.Best estimate of 658 + 397? (a) 1300 (b) 1100 (c) 900
  13. 13.Best estimate of 288 + 608? (a) 700 (b) 900 (c) 1100
  14. 14.Best estimate of 522 + 820? (a) 1300 (b) 1100 (c) 1500
  15. 15.Best estimate of 212 + 266? (a) 500 (b) 700 (c) 300
  16. 16.Best estimate of 56 × 48? (a) 300 (b) 3000 (c) 30000
  17. 17.Best estimate of 34 × 16? (a) 600 (b) 6000 (c) 60
  18. 18.Best estimate of 654 + 523? (a) 1400 (b) 1000 (c) 1200
  19. 19.Best estimate of 16 × 60? (a) 120 (b) 12000 (c) 1200
  20. 20.Best estimate of 361 + 385? (a) 800 (b) 1000 (c) 600
  21. 21.Best estimate of 86 × 46? (a) 4500 (b) 45000 (c) 450
  22. 22.Best estimate of 286 + 292? (a) 600 (b) 400 (c) 800
  23. 23.Best estimate of 89 × 56? (a) 540 (b) 54000 (c) 5400
  24. 24.Best estimate of 765 + 631? (a) 1200 (b) 1600 (c) 1400
  25. 25.Best estimate of 360 + 294? (a) 900 (b) 500 (c) 700
  26. 26.Best estimate of 130 + 827? (a) 700 (b) 1100 (c) 900
  27. 27.Best estimate of 86 × 54? (a) 45000 (b) 450 (c) 4500
  28. 28.Best estimate of 715 + 842? (a) 1500 (b) 1300 (c) 1700
  29. 29.Best estimate of 287 + 862? (a) 1400 (b) 1200 (c) 1000
  30. 30.Best estimate of 52 × 16? (a) 1000 (b) 10000 (c) 100
  31. 31.Best estimate of 19 × 62? (a) 1200 (b) 120 (c) 12000
  32. 32.Best estimate of 857 + 835? (a) 1700 (b) 1900 (c) 1500
  33. 33.Best estimate of 88 × 16? (a) 180 (b) 1800 (c) 18000
  34. 34.Best estimate of 49 × 91? (a) 450 (b) 45000 (c) 4500
  35. 35.Best estimate of 70 × 93? (a) 63000 (b) 630 (c) 6300
  36. 36.Best estimate of 21 × 69? (a) 1400 (b) 140 (c) 14000
  37. 37.Best estimate of 50 × 46? (a) 2500 (b) 25000 (c) 250
  38. 38.Best estimate of 59 × 18? (a) 12000 (b) 120 (c) 1200
  39. 39.Best estimate of 509 + 477? (a) 1200 (b) 1000 (c) 800
  40. 40.Best estimate of 22 × 24? (a) 400 (b) 4000 (c) 40

Answer key

  1. 400
  2. 500
  3. 600
  4. 600
  5. 3600
  6. 4900
  7. 7200
  8. 5600
  9. 6300
  10. 2100
  11. 2700
  12. 1100
  13. 900
  14. 1300
  15. 500
  16. 3000
  17. 600
  18. 1200
  19. 1200
  20. 800
  21. 4500
  22. 600
  23. 5400
  24. 1400
  25. 700
  26. 900
  27. 4500
  28. 1500
  29. 1200
  30. 1000
  31. 1200
  32. 1700
  33. 1800
  34. 4500
  35. 6300
  36. 1400
  37. 2500
  38. 1200
  39. 1000
  40. 400

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