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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 95 · 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 32 × 82? (a) 24000 (b) 2400 (c) 240
  2. 2.Best estimate of 26 × 36? (a) 1200 (b) 120 (c) 12000
  3. 3.Best estimate of 89 × 23? (a) 1800 (b) 18000 (c) 180
  4. 4.Best estimate of 149 + 784? (a) 1100 (b) 900 (c) 700
  5. 5.Best estimate of 30 × 30? (a) 90 (b) 9000 (c) 900
  6. 6.Best estimate of 76 × 29? (a) 24000 (b) 240 (c) 2400
  7. 7.Best estimate of 46 × 89? (a) 450 (b) 45000 (c) 4500
  8. 8.Best estimate of 58 × 98? (a) 600 (b) 6000 (c) 60000
  9. 9.Best estimate of 516 + 843? (a) 1300 (b) 1100 (c) 1500
  10. 10.Best estimate of 81 × 13? (a) 8000 (b) 800 (c) 80
  11. 11.Best estimate of 803 + 271? (a) 900 (b) 1100 (c) 1300
  12. 12.Best estimate of 37 × 72? (a) 280 (b) 2800 (c) 28000
  13. 13.Best estimate of 190 + 372? (a) 400 (b) 800 (c) 600
  14. 14.Best estimate of 47 × 70? (a) 35000 (b) 350 (c) 3500
  15. 15.Best estimate of 64 × 21? (a) 12000 (b) 1200 (c) 120
  16. 16.Best estimate of 325 + 637? (a) 700 (b) 900 (c) 1100
  17. 17.Best estimate of 266 + 837? (a) 900 (b) 1300 (c) 1100
  18. 18.Best estimate of 142 + 725? (a) 600 (b) 800 (c) 1000
  19. 19.Best estimate of 559 + 731? (a) 1100 (b) 1300 (c) 1500
  20. 20.Best estimate of 19 × 61? (a) 120 (b) 1200 (c) 12000
  21. 21.Best estimate of 36 × 23? (a) 800 (b) 80 (c) 8000
  22. 22.Best estimate of 91 × 88? (a) 8100 (b) 81000 (c) 810
  23. 23.Best estimate of 46 × 69? (a) 350 (b) 35000 (c) 3500
  24. 24.Best estimate of 83 × 87? (a) 720 (b) 7200 (c) 72000
  25. 25.Best estimate of 357 + 652? (a) 1300 (b) 900 (c) 1100
  26. 26.Best estimate of 313 + 586? (a) 700 (b) 900 (c) 1100
  27. 27.Best estimate of 133 + 215? (a) 100 (b) 500 (c) 300
  28. 28.Best estimate of 51 × 98? (a) 500 (b) 50000 (c) 5000
  29. 29.Best estimate of 511 + 686? (a) 1000 (b) 1400 (c) 1200
  30. 30.Best estimate of 273 + 852? (a) 1000 (b) 1400 (c) 1200
  31. 31.Best estimate of 770 + 269? (a) 900 (b) 1100 (c) 1300
  32. 32.Best estimate of 186 + 139? (a) 100 (b) 500 (c) 300
  33. 33.Best estimate of 26 × 86? (a) 2700 (b) 270 (c) 27000
  34. 34.Best estimate of 440 + 411? (a) 600 (b) 1000 (c) 800
  35. 35.Best estimate of 81 × 56? (a) 48000 (b) 480 (c) 4800
  36. 36.Best estimate of 225 + 835? (a) 1000 (b) 1200 (c) 800
  37. 37.Best estimate of 845 + 871? (a) 1500 (b) 1900 (c) 1700
  38. 38.Best estimate of 184 + 347? (a) 700 (b) 300 (c) 500
  39. 39.Best estimate of 57 × 33? (a) 1800 (b) 180 (c) 18000
  40. 40.Best estimate of 337 + 411? (a) 700 (b) 500 (c) 900

Answer key

  1. 2400
  2. 1200
  3. 1800
  4. 900
  5. 900
  6. 2400
  7. 4500
  8. 6000
  9. 1300
  10. 800
  11. 1100
  12. 2800
  13. 600
  14. 3500
  15. 1200
  16. 900
  17. 1100
  18. 800
  19. 1300
  20. 1200
  21. 800
  22. 8100
  23. 3500
  24. 7200
  25. 1100
  26. 900
  27. 300
  28. 5000
  29. 1200
  30. 1200
  31. 1100
  32. 300
  33. 2700
  34. 800
  35. 4800
  36. 1000
  37. 1700
  38. 500
  39. 1800
  40. 700

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