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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 308 · 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 76 × 24? (a) 16000 (b) 160 (c) 1600
  2. 2.Best estimate of 50 × 94? (a) 45000 (b) 4500 (c) 450
  3. 3.Best estimate of 36 × 48? (a) 200 (b) 2000 (c) 20000
  4. 4.Best estimate of 760 + 285? (a) 1300 (b) 1100 (c) 900
  5. 5.Best estimate of 97 × 51? (a) 5000 (b) 500 (c) 50000
  6. 6.Best estimate of 31 × 91? (a) 27000 (b) 270 (c) 2700
  7. 7.Best estimate of 84 × 64? (a) 480 (b) 48000 (c) 4800
  8. 8.Best estimate of 195 + 862? (a) 900 (b) 1300 (c) 1100
  9. 9.Best estimate of 777 + 255? (a) 1100 (b) 1300 (c) 900
  10. 10.Best estimate of 551 + 473? (a) 1300 (b) 1100 (c) 900
  11. 11.Best estimate of 303 + 583? (a) 900 (b) 1100 (c) 700
  12. 12.Best estimate of 527 + 655? (a) 1200 (b) 1000 (c) 1400
  13. 13.Best estimate of 97 × 16? (a) 20000 (b) 2000 (c) 200
  14. 14.Best estimate of 515 + 799? (a) 1300 (b) 1100 (c) 1500
  15. 15.Best estimate of 869 + 293? (a) 1200 (b) 1000 (c) 1400
  16. 16.Best estimate of 337 + 774? (a) 1100 (b) 1300 (c) 900
  17. 17.Best estimate of 260 + 409? (a) 500 (b) 900 (c) 700
  18. 18.Best estimate of 21 × 28? (a) 600 (b) 60 (c) 6000
  19. 19.Best estimate of 63 × 54? (a) 300 (b) 30000 (c) 3000
  20. 20.Best estimate of 43 × 98? (a) 400 (b) 4000 (c) 40000
  21. 21.Best estimate of 21 × 70? (a) 140 (b) 14000 (c) 1400
  22. 22.Best estimate of 481 + 327? (a) 800 (b) 1000 (c) 600
  23. 23.Best estimate of 314 + 785? (a) 1300 (b) 1100 (c) 900
  24. 24.Best estimate of 168 + 359? (a) 600 (b) 800 (c) 400
  25. 25.Best estimate of 27 × 21? (a) 60 (b) 600 (c) 6000
  26. 26.Best estimate of 82 × 41? (a) 320 (b) 3200 (c) 32000
  27. 27.Best estimate of 48 × 42? (a) 2000 (b) 200 (c) 20000
  28. 28.Best estimate of 433 + 648? (a) 1200 (b) 800 (c) 1000
  29. 29.Best estimate of 797 + 859? (a) 1500 (b) 1700 (c) 1900
  30. 30.Best estimate of 68 × 80? (a) 5600 (b) 56000 (c) 560
  31. 31.Best estimate of 805 + 872? (a) 1700 (b) 1900 (c) 1500
  32. 32.Best estimate of 26 × 48? (a) 15000 (b) 150 (c) 1500
  33. 33.Best estimate of 29 × 26? (a) 90 (b) 900 (c) 9000
  34. 34.Best estimate of 176 + 851? (a) 900 (b) 1300 (c) 1100
  35. 35.Best estimate of 731 + 625? (a) 1300 (b) 1500 (c) 1100
  36. 36.Best estimate of 508 + 701? (a) 1400 (b) 1000 (c) 1200
  37. 37.Best estimate of 20 × 49? (a) 1000 (b) 100 (c) 10000
  38. 38.Best estimate of 20 × 66? (a) 14000 (b) 1400 (c) 140
  39. 39.Best estimate of 337 + 221? (a) 700 (b) 500 (c) 300
  40. 40.Best estimate of 39 × 66? (a) 2800 (b) 280 (c) 28000

Answer key

  1. 1600
  2. 4500
  3. 2000
  4. 1100
  5. 5000
  6. 2700
  7. 4800
  8. 1100
  9. 1100
  10. 1100
  11. 900
  12. 1200
  13. 2000
  14. 1300
  15. 1200
  16. 1100
  17. 700
  18. 600
  19. 3000
  20. 4000
  21. 1400
  22. 800
  23. 1100
  24. 600
  25. 600
  26. 3200
  27. 2000
  28. 1000
  29. 1700
  30. 5600
  31. 1700
  32. 1500
  33. 900
  34. 1100
  35. 1300
  36. 1200
  37. 1000
  38. 1400
  39. 500
  40. 2800

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