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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 415 · 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 231 + 295? (a) 700 (b) 500 (c) 300
  2. 2.Best estimate of 73 × 13? (a) 700 (b) 70 (c) 7000
  3. 3.Best estimate of 599 + 781? (a) 1600 (b) 1400 (c) 1200
  4. 4.Best estimate of 49 × 14? (a) 5000 (b) 50 (c) 500
  5. 5.Best estimate of 221 + 482? (a) 900 (b) 500 (c) 700
  6. 6.Best estimate of 83 × 32? (a) 24000 (b) 240 (c) 2400
  7. 7.Best estimate of 27 × 72? (a) 210 (b) 21000 (c) 2100
  8. 8.Best estimate of 422 + 514? (a) 900 (b) 700 (c) 1100
  9. 9.Best estimate of 16 × 22? (a) 40 (b) 400 (c) 4000
  10. 10.Best estimate of 16 × 17? (a) 40 (b) 400 (c) 4000
  11. 11.Best estimate of 84 × 57? (a) 48000 (b) 480 (c) 4800
  12. 12.Best estimate of 781 + 197? (a) 1200 (b) 800 (c) 1000
  13. 13.Best estimate of 76 × 40? (a) 320 (b) 32000 (c) 3200
  14. 14.Best estimate of 32 × 93? (a) 270 (b) 27000 (c) 2700
  15. 15.Best estimate of 832 + 621? (a) 1600 (b) 1200 (c) 1400
  16. 16.Best estimate of 29 × 17? (a) 600 (b) 60 (c) 6000
  17. 17.Best estimate of 61 × 31? (a) 1800 (b) 18000 (c) 180
  18. 18.Best estimate of 834 + 156? (a) 1200 (b) 800 (c) 1000
  19. 19.Best estimate of 48 × 42? (a) 200 (b) 2000 (c) 20000
  20. 20.Best estimate of 423 + 482? (a) 1100 (b) 900 (c) 700
  21. 21.Best estimate of 526 + 853? (a) 1600 (b) 1400 (c) 1200
  22. 22.Best estimate of 694 + 297? (a) 1000 (b) 1200 (c) 800
  23. 23.Best estimate of 484 + 249? (a) 500 (b) 900 (c) 700
  24. 24.Best estimate of 484 + 334? (a) 800 (b) 1000 (c) 600
  25. 25.Best estimate of 86 × 16? (a) 18000 (b) 180 (c) 1800
  26. 26.Best estimate of 91 × 94? (a) 810 (b) 81000 (c) 8100
  27. 27.Best estimate of 26 × 91? (a) 27000 (b) 2700 (c) 270
  28. 28.Best estimate of 56 × 61? (a) 360 (b) 3600 (c) 36000
  29. 29.Best estimate of 91 × 49? (a) 45000 (b) 4500 (c) 450
  30. 30.Best estimate of 174 + 685? (a) 1100 (b) 700 (c) 900
  31. 31.Best estimate of 61 × 32? (a) 18000 (b) 1800 (c) 180
  32. 32.Best estimate of 736 + 797? (a) 1700 (b) 1500 (c) 1300
  33. 33.Best estimate of 312 + 427? (a) 500 (b) 900 (c) 700
  34. 34.Best estimate of 761 + 700? (a) 1700 (b) 1300 (c) 1500
  35. 35.Best estimate of 14 × 26? (a) 300 (b) 3000 (c) 30
  36. 36.Best estimate of 124 + 506? (a) 800 (b) 600 (c) 400
  37. 37.Best estimate of 51 × 70? (a) 3500 (b) 35000 (c) 350
  38. 38.Best estimate of 96 × 98? (a) 10000 (b) 1000 (c) 100000
  39. 39.Best estimate of 17 × 46? (a) 10000 (b) 100 (c) 1000
  40. 40.Best estimate of 77 × 46? (a) 4000 (b) 40000 (c) 400

Answer key

  1. 500
  2. 700
  3. 1400
  4. 500
  5. 700
  6. 2400
  7. 2100
  8. 900
  9. 400
  10. 400
  11. 4800
  12. 1000
  13. 3200
  14. 2700
  15. 1400
  16. 600
  17. 1800
  18. 1000
  19. 2000
  20. 900
  21. 1400
  22. 1000
  23. 700
  24. 800
  25. 1800
  26. 8100
  27. 2700
  28. 3600
  29. 4500
  30. 900
  31. 1800
  32. 1500
  33. 700
  34. 1500
  35. 300
  36. 600
  37. 3500
  38. 10000
  39. 1000
  40. 4000

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