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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 523 · 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 698 + 143? (a) 1000 (b) 600 (c) 800
  2. 2.Best estimate of 663 + 758? (a) 1500 (b) 1700 (c) 1300
  3. 3.Best estimate of 66 × 73? (a) 4900 (b) 49000 (c) 490
  4. 4.Best estimate of 22 × 80? (a) 160 (b) 1600 (c) 16000
  5. 5.Best estimate of 72 × 38? (a) 280 (b) 28000 (c) 2800
  6. 6.Best estimate of 692 + 365? (a) 1300 (b) 1100 (c) 900
  7. 7.Best estimate of 26 × 20? (a) 60 (b) 600 (c) 6000
  8. 8.Best estimate of 328 + 629? (a) 700 (b) 900 (c) 1100
  9. 9.Best estimate of 845 + 717? (a) 1700 (b) 1500 (c) 1300
  10. 10.Best estimate of 470 + 234? (a) 500 (b) 900 (c) 700
  11. 11.Best estimate of 471 + 765? (a) 1300 (b) 1500 (c) 1100
  12. 12.Best estimate of 97 × 33? (a) 3000 (b) 30000 (c) 300
  13. 13.Best estimate of 376 + 348? (a) 900 (b) 700 (c) 500
  14. 14.Best estimate of 684 + 776? (a) 1700 (b) 1300 (c) 1500
  15. 15.Best estimate of 23 × 89? (a) 18000 (b) 180 (c) 1800
  16. 16.Best estimate of 22 × 93? (a) 1800 (b) 18000 (c) 180
  17. 17.Best estimate of 498 + 496? (a) 1200 (b) 1000 (c) 800
  18. 18.Best estimate of 177 + 145? (a) 100 (b) 300 (c) 500
  19. 19.Best estimate of 17 × 21? (a) 4000 (b) 400 (c) 40
  20. 20.Best estimate of 447 + 136? (a) 500 (b) 700 (c) 300
  21. 21.Best estimate of 244 + 241? (a) 200 (b) 400 (c) 600
  22. 22.Best estimate of 769 + 537? (a) 1500 (b) 1100 (c) 1300
  23. 23.Best estimate of 679 + 785? (a) 1300 (b) 1700 (c) 1500
  24. 24.Best estimate of 342 + 356? (a) 700 (b) 900 (c) 500
  25. 25.Best estimate of 19 × 40? (a) 80 (b) 800 (c) 8000
  26. 26.Best estimate of 26 × 76? (a) 2400 (b) 24000 (c) 240
  27. 27.Best estimate of 61 × 26? (a) 1800 (b) 180 (c) 18000
  28. 28.Best estimate of 20 × 38? (a) 800 (b) 80 (c) 8000
  29. 29.Best estimate of 78 × 77? (a) 6400 (b) 64000 (c) 640
  30. 30.Best estimate of 48 × 49? (a) 2500 (b) 250 (c) 25000
  31. 31.Best estimate of 837 + 770? (a) 1600 (b) 1800 (c) 1400
  32. 32.Best estimate of 19 × 18? (a) 40 (b) 4000 (c) 400
  33. 33.Best estimate of 126 + 214? (a) 300 (b) 500 (c) 100
  34. 34.Best estimate of 54 × 94? (a) 450 (b) 45000 (c) 4500
  35. 35.Best estimate of 50 × 49? (a) 25000 (b) 250 (c) 2500
  36. 36.Best estimate of 769 + 328? (a) 1100 (b) 1300 (c) 900
  37. 37.Best estimate of 98 × 91? (a) 9000 (b) 900 (c) 90000
  38. 38.Best estimate of 72 × 62? (a) 420 (b) 4200 (c) 42000
  39. 39.Best estimate of 50 × 36? (a) 20000 (b) 200 (c) 2000
  40. 40.Best estimate of 464 + 431? (a) 1100 (b) 900 (c) 700

Answer key

  1. 800
  2. 1500
  3. 4900
  4. 1600
  5. 2800
  6. 1100
  7. 600
  8. 900
  9. 1500
  10. 700
  11. 1300
  12. 3000
  13. 700
  14. 1500
  15. 1800
  16. 1800
  17. 1000
  18. 300
  19. 400
  20. 500
  21. 400
  22. 1300
  23. 1500
  24. 700
  25. 800
  26. 2400
  27. 1800
  28. 800
  29. 6400
  30. 2500
  31. 1600
  32. 400
  33. 300
  34. 4500
  35. 2500
  36. 1100
  37. 9000
  38. 4200
  39. 2000
  40. 900

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