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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 900 · 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 77 × 22? (a) 160 (b) 16000 (c) 1600
  2. 2.Best estimate of 788 + 356? (a) 1200 (b) 1000 (c) 1400
  3. 3.Best estimate of 72 × 77? (a) 56000 (b) 5600 (c) 560
  4. 4.Best estimate of 38 × 77? (a) 32000 (b) 3200 (c) 320
  5. 5.Best estimate of 654 + 745? (a) 1600 (b) 1200 (c) 1400
  6. 6.Best estimate of 77 × 51? (a) 40000 (b) 400 (c) 4000
  7. 7.Best estimate of 783 + 617? (a) 1400 (b) 1600 (c) 1200
  8. 8.Best estimate of 517 + 770? (a) 1300 (b) 1500 (c) 1100
  9. 9.Best estimate of 28 × 77? (a) 2400 (b) 24000 (c) 240
  10. 10.Best estimate of 81 × 68? (a) 5600 (b) 56000 (c) 560
  11. 11.Best estimate of 44 × 56? (a) 240 (b) 24000 (c) 2400
  12. 12.Best estimate of 36 × 49? (a) 200 (b) 20000 (c) 2000
  13. 13.Best estimate of 725 + 506? (a) 1200 (b) 1000 (c) 1400
  14. 14.Best estimate of 38 × 84? (a) 3200 (b) 320 (c) 32000
  15. 15.Best estimate of 21 × 81? (a) 16000 (b) 160 (c) 1600
  16. 16.Best estimate of 51 × 26? (a) 15000 (b) 1500 (c) 150
  17. 17.Best estimate of 834 + 345? (a) 1100 (b) 1300 (c) 900
  18. 18.Best estimate of 86 × 30? (a) 2700 (b) 270 (c) 27000
  19. 19.Best estimate of 699 + 784? (a) 1300 (b) 1700 (c) 1500
  20. 20.Best estimate of 779 + 729? (a) 1500 (b) 1700 (c) 1300
  21. 21.Best estimate of 40 × 33? (a) 1200 (b) 120 (c) 12000
  22. 22.Best estimate of 306 + 196? (a) 500 (b) 300 (c) 700
  23. 23.Best estimate of 799 + 472? (a) 1300 (b) 1100 (c) 1500
  24. 24.Best estimate of 21 × 30? (a) 600 (b) 6000 (c) 60
  25. 25.Best estimate of 41 × 34? (a) 120 (b) 12000 (c) 1200
  26. 26.Best estimate of 220 + 649? (a) 800 (b) 600 (c) 1000
  27. 27.Best estimate of 766 + 448? (a) 1200 (b) 1400 (c) 1000
  28. 28.Best estimate of 355 + 120? (a) 700 (b) 500 (c) 300
  29. 29.Best estimate of 92 × 26? (a) 270 (b) 27000 (c) 2700
  30. 30.Best estimate of 661 + 772? (a) 1500 (b) 1300 (c) 1700
  31. 31.Best estimate of 140 + 143? (a) 200 (b) 0 (c) 400
  32. 32.Best estimate of 804 + 790? (a) 1800 (b) 1600 (c) 1400
  33. 33.Best estimate of 807 + 632? (a) 1200 (b) 1600 (c) 1400
  34. 34.Best estimate of 517 + 372? (a) 700 (b) 900 (c) 1100
  35. 35.Best estimate of 58 × 34? (a) 1800 (b) 18000 (c) 180
  36. 36.Best estimate of 170 + 170? (a) 400 (b) 600 (c) 200
  37. 37.Best estimate of 97 × 96? (a) 1000 (b) 100000 (c) 10000
  38. 38.Best estimate of 58 × 96? (a) 6000 (b) 60000 (c) 600
  39. 39.Best estimate of 59 × 46? (a) 3000 (b) 30000 (c) 300
  40. 40.Best estimate of 482 + 145? (a) 400 (b) 600 (c) 800

Answer key

  1. 1600
  2. 1200
  3. 5600
  4. 3200
  5. 1400
  6. 4000
  7. 1400
  8. 1300
  9. 2400
  10. 5600
  11. 2400
  12. 2000
  13. 1200
  14. 3200
  15. 1600
  16. 1500
  17. 1100
  18. 2700
  19. 1500
  20. 1500
  21. 1200
  22. 500
  23. 1300
  24. 600
  25. 1200
  26. 800
  27. 1200
  28. 500
  29. 2700
  30. 1500
  31. 200
  32. 1600
  33. 1400
  34. 900
  35. 1800
  36. 400
  37. 10000
  38. 6000
  39. 3000
  40. 600

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