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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 456 · 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 520 + 240? (a) 500 (b) 700 (c) 900
  2. 2.Best estimate of 93 × 49? (a) 45000 (b) 450 (c) 4500
  3. 3.Best estimate of 465 + 123? (a) 600 (b) 800 (c) 400
  4. 4.Best estimate of 501 + 435? (a) 700 (b) 900 (c) 1100
  5. 5.Best estimate of 56 × 96? (a) 6000 (b) 60000 (c) 600
  6. 6.Best estimate of 51 × 84? (a) 400 (b) 4000 (c) 40000
  7. 7.Best estimate of 266 + 375? (a) 900 (b) 500 (c) 700
  8. 8.Best estimate of 27 × 87? (a) 270 (b) 27000 (c) 2700
  9. 9.Best estimate of 651 + 375? (a) 900 (b) 1300 (c) 1100
  10. 10.Best estimate of 69 × 59? (a) 42000 (b) 4200 (c) 420
  11. 11.Best estimate of 97 × 72? (a) 70000 (b) 7000 (c) 700
  12. 12.Best estimate of 235 + 473? (a) 700 (b) 900 (c) 500
  13. 13.Best estimate of 281 + 662? (a) 1200 (b) 1000 (c) 800
  14. 14.Best estimate of 26 × 52? (a) 150 (b) 15000 (c) 1500
  15. 15.Best estimate of 41 × 38? (a) 16000 (b) 160 (c) 1600
  16. 16.Best estimate of 205 + 141? (a) 500 (b) 300 (c) 100
  17. 17.Best estimate of 540 + 442? (a) 900 (b) 1100 (c) 700
  18. 18.Best estimate of 147 + 379? (a) 500 (b) 300 (c) 700
  19. 19.Best estimate of 805 + 651? (a) 1300 (b) 1500 (c) 1700
  20. 20.Best estimate of 165 + 416? (a) 600 (b) 800 (c) 400
  21. 21.Best estimate of 327 + 847? (a) 1100 (b) 900 (c) 1300
  22. 22.Best estimate of 148 + 124? (a) 200 (b) 0 (c) 400
  23. 23.Best estimate of 184 + 540? (a) 700 (b) 900 (c) 500
  24. 24.Best estimate of 871 + 682? (a) 1800 (b) 1400 (c) 1600
  25. 25.Best estimate of 90 × 92? (a) 810 (b) 8100 (c) 81000
  26. 26.Best estimate of 96 × 96? (a) 100000 (b) 1000 (c) 10000
  27. 27.Best estimate of 243 + 139? (a) 100 (b) 300 (c) 500
  28. 28.Best estimate of 79 × 31? (a) 2400 (b) 240 (c) 24000
  29. 29.Best estimate of 214 + 507? (a) 700 (b) 900 (c) 500
  30. 30.Best estimate of 64 × 90? (a) 54000 (b) 5400 (c) 540
  31. 31.Best estimate of 675 + 202? (a) 700 (b) 900 (c) 1100
  32. 32.Best estimate of 388 + 596? (a) 1200 (b) 1000 (c) 800
  33. 33.Best estimate of 78 × 80? (a) 640 (b) 6400 (c) 64000
  34. 34.Best estimate of 16 × 27? (a) 600 (b) 6000 (c) 60
  35. 35.Best estimate of 492 + 678? (a) 1200 (b) 1000 (c) 1400
  36. 36.Best estimate of 36 × 39? (a) 160 (b) 16000 (c) 1600
  37. 37.Best estimate of 482 + 283? (a) 1000 (b) 600 (c) 800
  38. 38.Best estimate of 307 + 732? (a) 1000 (b) 800 (c) 1200
  39. 39.Best estimate of 36 × 40? (a) 16000 (b) 160 (c) 1600
  40. 40.Best estimate of 16 × 16? (a) 400 (b) 40 (c) 4000

Answer key

  1. 700
  2. 4500
  3. 600
  4. 900
  5. 6000
  6. 4000
  7. 700
  8. 2700
  9. 1100
  10. 4200
  11. 7000
  12. 700
  13. 1000
  14. 1500
  15. 1600
  16. 300
  17. 900
  18. 500
  19. 1500
  20. 600
  21. 1100
  22. 200
  23. 700
  24. 1600
  25. 8100
  26. 10000
  27. 300
  28. 2400
  29. 700
  30. 5400
  31. 900
  32. 1000
  33. 6400
  34. 600
  35. 1200
  36. 1600
  37. 800
  38. 1000
  39. 1600
  40. 400

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