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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 470 · 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 214 + 540? (a) 900 (b) 500 (c) 700
  2. 2.Best estimate of 53 × 86? (a) 45000 (b) 4500 (c) 450
  3. 3.Best estimate of 151 + 160? (a) 600 (b) 200 (c) 400
  4. 4.Best estimate of 360 + 404? (a) 800 (b) 600 (c) 1000
  5. 5.Best estimate of 26 × 59? (a) 1800 (b) 18000 (c) 180
  6. 6.Best estimate of 190 + 206? (a) 400 (b) 200 (c) 600
  7. 7.Best estimate of 96 × 88? (a) 90000 (b) 9000 (c) 900
  8. 8.Best estimate of 218 + 664? (a) 1100 (b) 700 (c) 900
  9. 9.Best estimate of 90 × 29? (a) 270 (b) 27000 (c) 2700
  10. 10.Best estimate of 90 × 52? (a) 4500 (b) 45000 (c) 450
  11. 11.Best estimate of 879 + 184? (a) 900 (b) 1300 (c) 1100
  12. 12.Best estimate of 834 + 670? (a) 1500 (b) 1300 (c) 1700
  13. 13.Best estimate of 535 + 569? (a) 1300 (b) 900 (c) 1100
  14. 14.Best estimate of 42 × 86? (a) 3600 (b) 360 (c) 36000
  15. 15.Best estimate of 21 × 47? (a) 100 (b) 1000 (c) 10000
  16. 16.Best estimate of 80 × 94? (a) 720 (b) 7200 (c) 72000
  17. 17.Best estimate of 405 + 683? (a) 1100 (b) 900 (c) 1300
  18. 18.Best estimate of 651 + 498? (a) 1200 (b) 1000 (c) 1400
  19. 19.Best estimate of 56 × 71? (a) 420 (b) 4200 (c) 42000
  20. 20.Best estimate of 78 × 67? (a) 56000 (b) 560 (c) 5600
  21. 21.Best estimate of 70 × 33? (a) 210 (b) 21000 (c) 2100
  22. 22.Best estimate of 26 × 46? (a) 150 (b) 1500 (c) 15000
  23. 23.Best estimate of 155 + 300? (a) 500 (b) 300 (c) 700
  24. 24.Best estimate of 36 × 53? (a) 2000 (b) 200 (c) 20000
  25. 25.Best estimate of 268 + 218? (a) 300 (b) 500 (c) 700
  26. 26.Best estimate of 46 × 97? (a) 50000 (b) 5000 (c) 500
  27. 27.Best estimate of 833 + 530? (a) 1300 (b) 1100 (c) 1500
  28. 28.Best estimate of 198 + 384? (a) 600 (b) 400 (c) 800
  29. 29.Best estimate of 166 + 432? (a) 400 (b) 800 (c) 600
  30. 30.Best estimate of 98 × 12? (a) 100 (b) 10000 (c) 1000
  31. 31.Best estimate of 88 × 38? (a) 3600 (b) 360 (c) 36000
  32. 32.Best estimate of 56 × 86? (a) 5400 (b) 54000 (c) 540
  33. 33.Best estimate of 18 × 43? (a) 8000 (b) 80 (c) 800
  34. 34.Best estimate of 470 + 479? (a) 1000 (b) 800 (c) 1200
  35. 35.Best estimate of 610 + 864? (a) 1300 (b) 1700 (c) 1500
  36. 36.Best estimate of 21 × 73? (a) 1400 (b) 140 (c) 14000
  37. 37.Best estimate of 535 + 851? (a) 1400 (b) 1200 (c) 1600
  38. 38.Best estimate of 31 × 17? (a) 60 (b) 600 (c) 6000
  39. 39.Best estimate of 14 × 73? (a) 70 (b) 700 (c) 7000
  40. 40.Best estimate of 589 + 749? (a) 1300 (b) 1100 (c) 1500

Answer key

  1. 700
  2. 4500
  3. 400
  4. 800
  5. 1800
  6. 400
  7. 9000
  8. 900
  9. 2700
  10. 4500
  11. 1100
  12. 1500
  13. 1100
  14. 3600
  15. 1000
  16. 7200
  17. 1100
  18. 1200
  19. 4200
  20. 5600
  21. 2100
  22. 1500
  23. 500
  24. 2000
  25. 500
  26. 5000
  27. 1300
  28. 600
  29. 600
  30. 1000
  31. 3600
  32. 5400
  33. 800
  34. 1000
  35. 1500
  36. 1400
  37. 1400
  38. 600
  39. 700
  40. 1300

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