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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 559 · 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 133 + 636? (a) 500 (b) 700 (c) 900
  2. 2.Best estimate of 354 + 551? (a) 1200 (b) 1000 (c) 800
  3. 3.Best estimate of 641 + 670? (a) 1100 (b) 1300 (c) 1500
  4. 4.Best estimate of 56 × 24? (a) 1200 (b) 12000 (c) 120
  5. 5.Best estimate of 60 × 68? (a) 42000 (b) 420 (c) 4200
  6. 6.Best estimate of 181 + 773? (a) 1200 (b) 800 (c) 1000
  7. 7.Best estimate of 54 × 53? (a) 25000 (b) 2500 (c) 250
  8. 8.Best estimate of 182 + 854? (a) 1100 (b) 900 (c) 1300
  9. 9.Best estimate of 493 + 140? (a) 600 (b) 400 (c) 800
  10. 10.Best estimate of 56 × 91? (a) 5400 (b) 54000 (c) 540
  11. 11.Best estimate of 367 + 407? (a) 600 (b) 1000 (c) 800
  12. 12.Best estimate of 849 + 584? (a) 1400 (b) 1600 (c) 1200
  13. 13.Best estimate of 835 + 161? (a) 800 (b) 1000 (c) 1200
  14. 14.Best estimate of 159 + 155? (a) 600 (b) 200 (c) 400
  15. 15.Best estimate of 868 + 639? (a) 1500 (b) 1300 (c) 1700
  16. 16.Best estimate of 66 × 74? (a) 4900 (b) 49000 (c) 490
  17. 17.Best estimate of 19 × 36? (a) 80 (b) 8000 (c) 800
  18. 18.Best estimate of 788 + 331? (a) 1300 (b) 900 (c) 1100
  19. 19.Best estimate of 52 × 66? (a) 3500 (b) 35000 (c) 350
  20. 20.Best estimate of 74 × 22? (a) 14000 (b) 1400 (c) 140
  21. 21.Best estimate of 346 + 700? (a) 1200 (b) 1000 (c) 800
  22. 22.Best estimate of 72 × 44? (a) 2800 (b) 28000 (c) 280
  23. 23.Best estimate of 621 + 401? (a) 1200 (b) 800 (c) 1000
  24. 24.Best estimate of 33 × 32? (a) 900 (b) 90 (c) 9000
  25. 25.Best estimate of 32 × 57? (a) 1800 (b) 180 (c) 18000
  26. 26.Best estimate of 318 + 500? (a) 600 (b) 1000 (c) 800
  27. 27.Best estimate of 17 × 12? (a) 2000 (b) 200 (c) 20
  28. 28.Best estimate of 97 × 23? (a) 200 (b) 2000 (c) 20000
  29. 29.Best estimate of 464 + 543? (a) 1000 (b) 800 (c) 1200
  30. 30.Best estimate of 58 × 96? (a) 60000 (b) 600 (c) 6000
  31. 31.Best estimate of 23 × 61? (a) 1200 (b) 120 (c) 12000
  32. 32.Best estimate of 37 × 83? (a) 3200 (b) 32000 (c) 320
  33. 33.Best estimate of 346 + 137? (a) 600 (b) 400 (c) 200
  34. 34.Best estimate of 97 × 52? (a) 50000 (b) 5000 (c) 500
  35. 35.Best estimate of 50 × 68? (a) 3500 (b) 35000 (c) 350
  36. 36.Best estimate of 179 + 221? (a) 200 (b) 600 (c) 400
  37. 37.Best estimate of 729 + 265? (a) 1000 (b) 1200 (c) 800
  38. 38.Best estimate of 792 + 571? (a) 1400 (b) 1200 (c) 1600
  39. 39.Best estimate of 37 × 74? (a) 28000 (b) 280 (c) 2800
  40. 40.Best estimate of 143 + 747? (a) 600 (b) 1000 (c) 800

Answer key

  1. 700
  2. 1000
  3. 1300
  4. 1200
  5. 4200
  6. 1000
  7. 2500
  8. 1100
  9. 600
  10. 5400
  11. 800
  12. 1400
  13. 1000
  14. 400
  15. 1500
  16. 4900
  17. 800
  18. 1100
  19. 3500
  20. 1400
  21. 1000
  22. 2800
  23. 1000
  24. 900
  25. 1800
  26. 800
  27. 200
  28. 2000
  29. 1000
  30. 6000
  31. 1200
  32. 3200
  33. 400
  34. 5000
  35. 3500
  36. 400
  37. 1000
  38. 1400
  39. 2800
  40. 800

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