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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 72 · 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 66 × 51? (a) 35000 (b) 3500 (c) 350
  2. 2.Best estimate of 76 × 98? (a) 800 (b) 80000 (c) 8000
  3. 3.Best estimate of 151 + 169? (a) 400 (b) 200 (c) 600
  4. 4.Best estimate of 71 × 14? (a) 7000 (b) 700 (c) 70
  5. 5.Best estimate of 302 + 438? (a) 500 (b) 700 (c) 900
  6. 6.Best estimate of 623 + 802? (a) 1400 (b) 1600 (c) 1200
  7. 7.Best estimate of 675 + 810? (a) 1700 (b) 1300 (c) 1500
  8. 8.Best estimate of 13 × 31? (a) 30 (b) 300 (c) 3000
  9. 9.Best estimate of 503 + 807? (a) 1300 (b) 1500 (c) 1100
  10. 10.Best estimate of 31 × 22? (a) 600 (b) 6000 (c) 60
  11. 11.Best estimate of 214 + 434? (a) 600 (b) 400 (c) 800
  12. 12.Best estimate of 435 + 273? (a) 500 (b) 700 (c) 900
  13. 13.Best estimate of 14 × 93? (a) 90 (b) 900 (c) 9000
  14. 14.Best estimate of 92 × 30? (a) 27000 (b) 270 (c) 2700
  15. 15.Best estimate of 398 + 859? (a) 1500 (b) 1100 (c) 1300
  16. 16.Best estimate of 520 + 392? (a) 1100 (b) 900 (c) 700
  17. 17.Best estimate of 52 × 51? (a) 25000 (b) 2500 (c) 250
  18. 18.Best estimate of 243 + 549? (a) 700 (b) 900 (c) 500
  19. 19.Best estimate of 432 + 755? (a) 1000 (b) 1400 (c) 1200
  20. 20.Best estimate of 440 + 454? (a) 700 (b) 900 (c) 1100
  21. 21.Best estimate of 19 × 28? (a) 6000 (b) 600 (c) 60
  22. 22.Best estimate of 470 + 554? (a) 1100 (b) 1300 (c) 900
  23. 23.Best estimate of 86 × 82? (a) 720 (b) 7200 (c) 72000
  24. 24.Best estimate of 180 + 273? (a) 300 (b) 500 (c) 700
  25. 25.Best estimate of 312 + 264? (a) 600 (b) 800 (c) 400
  26. 26.Best estimate of 147 + 643? (a) 500 (b) 700 (c) 900
  27. 27.Best estimate of 484 + 685? (a) 1200 (b) 1400 (c) 1000
  28. 28.Best estimate of 56 × 73? (a) 420 (b) 4200 (c) 42000
  29. 29.Best estimate of 56 × 26? (a) 180 (b) 18000 (c) 1800
  30. 30.Best estimate of 601 + 546? (a) 900 (b) 1300 (c) 1100
  31. 31.Best estimate of 38 × 17? (a) 800 (b) 8000 (c) 80
  32. 32.Best estimate of 591 + 576? (a) 1400 (b) 1000 (c) 1200
  33. 33.Best estimate of 22 × 47? (a) 100 (b) 1000 (c) 10000
  34. 34.Best estimate of 678 + 409? (a) 1300 (b) 900 (c) 1100
  35. 35.Best estimate of 57 × 98? (a) 6000 (b) 60000 (c) 600
  36. 36.Best estimate of 271 + 762? (a) 900 (b) 1100 (c) 1300
  37. 37.Best estimate of 446 + 692? (a) 900 (b) 1300 (c) 1100
  38. 38.Best estimate of 297 + 174? (a) 500 (b) 700 (c) 300
  39. 39.Best estimate of 468 + 773? (a) 1500 (b) 1100 (c) 1300
  40. 40.Best estimate of 735 + 686? (a) 1400 (b) 1600 (c) 1200

Answer key

  1. 3500
  2. 8000
  3. 400
  4. 700
  5. 700
  6. 1400
  7. 1500
  8. 300
  9. 1300
  10. 600
  11. 600
  12. 700
  13. 900
  14. 2700
  15. 1300
  16. 900
  17. 2500
  18. 700
  19. 1200
  20. 900
  21. 600
  22. 1100
  23. 7200
  24. 500
  25. 600
  26. 700
  27. 1200
  28. 4200
  29. 1800
  30. 1100
  31. 800
  32. 1200
  33. 1000
  34. 1100
  35. 6000
  36. 1100
  37. 1100
  38. 500
  39. 1300
  40. 1400

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