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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 149 · 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 202 + 363? (a) 800 (b) 400 (c) 600
  2. 2.Best estimate of 59 × 12? (a) 6000 (b) 60 (c) 600
  3. 3.Best estimate of 632 + 260? (a) 900 (b) 1100 (c) 700
  4. 4.Best estimate of 683 + 845? (a) 1300 (b) 1500 (c) 1700
  5. 5.Best estimate of 69 × 23? (a) 140 (b) 1400 (c) 14000
  6. 6.Best estimate of 224 + 726? (a) 1100 (b) 700 (c) 900
  7. 7.Best estimate of 53 × 29? (a) 1500 (b) 150 (c) 15000
  8. 8.Best estimate of 97 × 88? (a) 9000 (b) 900 (c) 90000
  9. 9.Best estimate of 717 + 481? (a) 1000 (b) 1200 (c) 1400
  10. 10.Best estimate of 18 × 31? (a) 600 (b) 6000 (c) 60
  11. 11.Best estimate of 32 × 39? (a) 1200 (b) 12000 (c) 120
  12. 12.Best estimate of 764 + 602? (a) 1400 (b) 1200 (c) 1600
  13. 13.Best estimate of 368 + 433? (a) 800 (b) 600 (c) 1000
  14. 14.Best estimate of 31 × 36? (a) 120 (b) 1200 (c) 12000
  15. 15.Best estimate of 17 × 34? (a) 600 (b) 60 (c) 6000
  16. 16.Best estimate of 224 + 665? (a) 900 (b) 1100 (c) 700
  17. 17.Best estimate of 181 + 654? (a) 700 (b) 1100 (c) 900
  18. 18.Best estimate of 141 + 591? (a) 900 (b) 500 (c) 700
  19. 19.Best estimate of 564 + 178? (a) 600 (b) 800 (c) 1000
  20. 20.Best estimate of 781 + 567? (a) 1400 (b) 1200 (c) 1600
  21. 21.Best estimate of 782 + 371? (a) 1400 (b) 1000 (c) 1200
  22. 22.Best estimate of 80 × 50? (a) 4000 (b) 400 (c) 40000
  23. 23.Best estimate of 51 × 70? (a) 3500 (b) 350 (c) 35000
  24. 24.Best estimate of 80 × 73? (a) 56000 (b) 5600 (c) 560
  25. 25.Best estimate of 58 × 21? (a) 12000 (b) 1200 (c) 120
  26. 26.Best estimate of 143 + 799? (a) 700 (b) 900 (c) 1100
  27. 27.Best estimate of 80 × 23? (a) 1600 (b) 160 (c) 16000
  28. 28.Best estimate of 168 + 870? (a) 1100 (b) 1300 (c) 900
  29. 29.Best estimate of 489 + 762? (a) 1500 (b) 1300 (c) 1100
  30. 30.Best estimate of 18 × 37? (a) 8000 (b) 80 (c) 800
  31. 31.Best estimate of 16 × 30? (a) 60 (b) 6000 (c) 600
  32. 32.Best estimate of 59 × 90? (a) 5400 (b) 540 (c) 54000
  33. 33.Best estimate of 30 × 42? (a) 12000 (b) 1200 (c) 120
  34. 34.Best estimate of 686 + 218? (a) 900 (b) 1100 (c) 700
  35. 35.Best estimate of 36 × 48? (a) 2000 (b) 200 (c) 20000
  36. 36.Best estimate of 290 + 808? (a) 1100 (b) 900 (c) 1300
  37. 37.Best estimate of 19 × 32? (a) 60 (b) 600 (c) 6000
  38. 38.Best estimate of 98 × 52? (a) 5000 (b) 50000 (c) 500
  39. 39.Best estimate of 463 + 220? (a) 700 (b) 500 (c) 900
  40. 40.Best estimate of 78 × 16? (a) 16000 (b) 1600 (c) 160

Answer key

  1. 600
  2. 600
  3. 900
  4. 1500
  5. 1400
  6. 900
  7. 1500
  8. 9000
  9. 1200
  10. 600
  11. 1200
  12. 1400
  13. 800
  14. 1200
  15. 600
  16. 900
  17. 900
  18. 700
  19. 800
  20. 1400
  21. 1200
  22. 4000
  23. 3500
  24. 5600
  25. 1200
  26. 900
  27. 1600
  28. 1100
  29. 1300
  30. 800
  31. 600
  32. 5400
  33. 1200
  34. 900
  35. 2000
  36. 1100
  37. 600
  38. 5000
  39. 700
  40. 1600

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