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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 996 · 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 48 × 54? (a) 25000 (b) 250 (c) 2500
  2. 2.Best estimate of 50 × 79? (a) 400 (b) 4000 (c) 40000
  3. 3.Best estimate of 22 × 76? (a) 16000 (b) 1600 (c) 160
  4. 4.Best estimate of 49 × 93? (a) 4500 (b) 45000 (c) 450
  5. 5.Best estimate of 73 × 26? (a) 210 (b) 2100 (c) 21000
  6. 6.Best estimate of 53 × 66? (a) 3500 (b) 350 (c) 35000
  7. 7.Best estimate of 331 + 152? (a) 700 (b) 500 (c) 300
  8. 8.Best estimate of 56 × 26? (a) 180 (b) 1800 (c) 18000
  9. 9.Best estimate of 14 × 16? (a) 200 (b) 20 (c) 2000
  10. 10.Best estimate of 172 + 357? (a) 400 (b) 800 (c) 600
  11. 11.Best estimate of 655 + 260? (a) 1000 (b) 1200 (c) 800
  12. 12.Best estimate of 699 + 401? (a) 1300 (b) 900 (c) 1100
  13. 13.Best estimate of 67 × 30? (a) 21000 (b) 2100 (c) 210
  14. 14.Best estimate of 21 × 36? (a) 800 (b) 80 (c) 8000
  15. 15.Best estimate of 16 × 16? (a) 4000 (b) 400 (c) 40
  16. 16.Best estimate of 57 × 68? (a) 4200 (b) 420 (c) 42000
  17. 17.Best estimate of 322 + 417? (a) 900 (b) 700 (c) 500
  18. 18.Best estimate of 62 × 92? (a) 5400 (b) 54000 (c) 540
  19. 19.Best estimate of 60 × 56? (a) 3600 (b) 36000 (c) 360
  20. 20.Best estimate of 668 + 125? (a) 800 (b) 1000 (c) 600
  21. 21.Best estimate of 576 + 828? (a) 1400 (b) 1600 (c) 1200
  22. 22.Best estimate of 66 × 59? (a) 420 (b) 42000 (c) 4200
  23. 23.Best estimate of 240 + 307? (a) 700 (b) 500 (c) 300
  24. 24.Best estimate of 854 + 673? (a) 1400 (b) 1600 (c) 1800
  25. 25.Best estimate of 238 + 773? (a) 1200 (b) 1000 (c) 800
  26. 26.Best estimate of 98 × 38? (a) 40000 (b) 400 (c) 4000
  27. 27.Best estimate of 215 + 688? (a) 700 (b) 900 (c) 1100
  28. 28.Best estimate of 791 + 287? (a) 900 (b) 1100 (c) 1300
  29. 29.Best estimate of 31 × 97? (a) 30000 (b) 3000 (c) 300
  30. 30.Best estimate of 62 × 41? (a) 2400 (b) 240 (c) 24000
  31. 31.Best estimate of 786 + 306? (a) 1300 (b) 900 (c) 1100
  32. 32.Best estimate of 46 × 98? (a) 500 (b) 50000 (c) 5000
  33. 33.Best estimate of 123 + 448? (a) 500 (b) 700 (c) 300
  34. 34.Best estimate of 46 × 37? (a) 20000 (b) 2000 (c) 200
  35. 35.Best estimate of 383 + 258? (a) 900 (b) 500 (c) 700
  36. 36.Best estimate of 436 + 681? (a) 1100 (b) 900 (c) 1300
  37. 37.Best estimate of 842 + 364? (a) 1000 (b) 1400 (c) 1200
  38. 38.Best estimate of 500 + 393? (a) 1100 (b) 700 (c) 900
  39. 39.Best estimate of 60 × 26? (a) 18000 (b) 180 (c) 1800
  40. 40.Best estimate of 481 + 580? (a) 1300 (b) 900 (c) 1100

Answer key

  1. 2500
  2. 4000
  3. 1600
  4. 4500
  5. 2100
  6. 3500
  7. 500
  8. 1800
  9. 200
  10. 600
  11. 1000
  12. 1100
  13. 2100
  14. 800
  15. 400
  16. 4200
  17. 700
  18. 5400
  19. 3600
  20. 800
  21. 1400
  22. 4200
  23. 500
  24. 1600
  25. 1000
  26. 4000
  27. 900
  28. 1100
  29. 3000
  30. 2400
  31. 1100
  32. 5000
  33. 500
  34. 2000
  35. 700
  36. 1100
  37. 1200
  38. 900
  39. 1800
  40. 1100

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