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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 102 · 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 × 59? (a) 3600 (b) 360 (c) 36000
  2. 2.Best estimate of 644 + 591? (a) 1000 (b) 1400 (c) 1200
  3. 3.Best estimate of 46 × 86? (a) 450 (b) 4500 (c) 45000
  4. 4.Best estimate of 53 × 26? (a) 15000 (b) 150 (c) 1500
  5. 5.Best estimate of 660 + 740? (a) 1400 (b) 1200 (c) 1600
  6. 6.Best estimate of 13 × 26? (a) 3000 (b) 300 (c) 30
  7. 7.Best estimate of 89 × 74? (a) 63000 (b) 630 (c) 6300
  8. 8.Best estimate of 44 × 96? (a) 400 (b) 4000 (c) 40000
  9. 9.Best estimate of 779 + 585? (a) 1600 (b) 1400 (c) 1200
  10. 10.Best estimate of 856 + 610? (a) 1300 (b) 1500 (c) 1700
  11. 11.Best estimate of 40 × 82? (a) 320 (b) 32000 (c) 3200
  12. 12.Best estimate of 86 × 48? (a) 4500 (b) 45000 (c) 450
  13. 13.Best estimate of 67 × 76? (a) 56000 (b) 5600 (c) 560
  14. 14.Best estimate of 675 + 358? (a) 1300 (b) 1100 (c) 900
  15. 15.Best estimate of 16 × 71? (a) 14000 (b) 1400 (c) 140
  16. 16.Best estimate of 407 + 586? (a) 1000 (b) 1200 (c) 800
  17. 17.Best estimate of 337 + 644? (a) 700 (b) 900 (c) 1100
  18. 18.Best estimate of 21 × 73? (a) 140 (b) 14000 (c) 1400
  19. 19.Best estimate of 59 × 68? (a) 42000 (b) 4200 (c) 420
  20. 20.Best estimate of 625 + 387? (a) 1200 (b) 1000 (c) 800
  21. 21.Best estimate of 77 × 53? (a) 4000 (b) 40000 (c) 400
  22. 22.Best estimate of 18 × 69? (a) 1400 (b) 14000 (c) 140
  23. 23.Best estimate of 26 × 30? (a) 9000 (b) 900 (c) 90
  24. 24.Best estimate of 490 + 593? (a) 1300 (b) 900 (c) 1100
  25. 25.Best estimate of 798 + 287? (a) 900 (b) 1100 (c) 1300
  26. 26.Best estimate of 98 × 16? (a) 2000 (b) 20000 (c) 200
  27. 27.Best estimate of 64 × 18? (a) 12000 (b) 120 (c) 1200
  28. 28.Best estimate of 27 × 89? (a) 2700 (b) 27000 (c) 270
  29. 29.Best estimate of 18 × 54? (a) 10000 (b) 1000 (c) 100
  30. 30.Best estimate of 13 × 29? (a) 300 (b) 30 (c) 3000
  31. 31.Best estimate of 22 × 69? (a) 1400 (b) 140 (c) 14000
  32. 32.Best estimate of 608 + 233? (a) 1000 (b) 800 (c) 600
  33. 33.Best estimate of 57 × 40? (a) 240 (b) 2400 (c) 24000
  34. 34.Best estimate of 343 + 627? (a) 700 (b) 1100 (c) 900
  35. 35.Best estimate of 66 × 68? (a) 4900 (b) 49000 (c) 490
  36. 36.Best estimate of 322 + 421? (a) 500 (b) 900 (c) 700
  37. 37.Best estimate of 41 × 88? (a) 360 (b) 3600 (c) 36000
  38. 38.Best estimate of 52 × 33? (a) 15000 (b) 1500 (c) 150
  39. 39.Best estimate of 376 + 533? (a) 700 (b) 1100 (c) 900
  40. 40.Best estimate of 80 × 26? (a) 240 (b) 24000 (c) 2400

Answer key

  1. 3600
  2. 1200
  3. 4500
  4. 1500
  5. 1400
  6. 300
  7. 6300
  8. 4000
  9. 1400
  10. 1500
  11. 3200
  12. 4500
  13. 5600
  14. 1100
  15. 1400
  16. 1000
  17. 900
  18. 1400
  19. 4200
  20. 1000
  21. 4000
  22. 1400
  23. 900
  24. 1100
  25. 1100
  26. 2000
  27. 1200
  28. 2700
  29. 1000
  30. 300
  31. 1400
  32. 800
  33. 2400
  34. 900
  35. 4900
  36. 700
  37. 3600
  38. 1500
  39. 900
  40. 2400

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