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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 834 · 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 168 + 432? (a) 600 (b) 800 (c) 400
  2. 2.Best estimate of 758 + 784? (a) 1800 (b) 1600 (c) 1400
  3. 3.Best estimate of 128 + 399? (a) 300 (b) 700 (c) 500
  4. 4.Best estimate of 73 × 66? (a) 4900 (b) 49000 (c) 490
  5. 5.Best estimate of 449 + 870? (a) 1100 (b) 1300 (c) 1500
  6. 6.Best estimate of 38 × 93? (a) 3600 (b) 36000 (c) 360
  7. 7.Best estimate of 46 × 16? (a) 1000 (b) 10000 (c) 100
  8. 8.Best estimate of 312 + 155? (a) 500 (b) 700 (c) 300
  9. 9.Best estimate of 21 × 76? (a) 1600 (b) 16000 (c) 160
  10. 10.Best estimate of 852 + 270? (a) 1400 (b) 1000 (c) 1200
  11. 11.Best estimate of 357 + 658? (a) 1100 (b) 1300 (c) 900
  12. 12.Best estimate of 47 × 12? (a) 500 (b) 50 (c) 5000
  13. 13.Best estimate of 50 × 56? (a) 300 (b) 30000 (c) 3000
  14. 14.Best estimate of 73 × 74? (a) 4900 (b) 490 (c) 49000
  15. 15.Best estimate of 873 + 210? (a) 900 (b) 1100 (c) 1300
  16. 16.Best estimate of 313 + 724? (a) 800 (b) 1000 (c) 1200
  17. 17.Best estimate of 636 + 678? (a) 1500 (b) 1300 (c) 1100
  18. 18.Best estimate of 803 + 653? (a) 1700 (b) 1300 (c) 1500
  19. 19.Best estimate of 29 × 53? (a) 15000 (b) 1500 (c) 150
  20. 20.Best estimate of 42 × 28? (a) 12000 (b) 120 (c) 1200
  21. 21.Best estimate of 96 × 69? (a) 7000 (b) 700 (c) 70000
  22. 22.Best estimate of 660 + 251? (a) 1000 (b) 1200 (c) 800
  23. 23.Best estimate of 26 × 27? (a) 90 (b) 9000 (c) 900
  24. 24.Best estimate of 874 + 675? (a) 1800 (b) 1600 (c) 1400
  25. 25.Best estimate of 853 + 245? (a) 1300 (b) 1100 (c) 900
  26. 26.Best estimate of 151 + 216? (a) 200 (b) 600 (c) 400
  27. 27.Best estimate of 169 + 211? (a) 600 (b) 200 (c) 400
  28. 28.Best estimate of 88 × 82? (a) 720 (b) 7200 (c) 72000
  29. 29.Best estimate of 142 + 441? (a) 500 (b) 300 (c) 700
  30. 30.Best estimate of 63 × 24? (a) 12000 (b) 1200 (c) 120
  31. 31.Best estimate of 12 × 14? (a) 10 (b) 1000 (c) 100
  32. 32.Best estimate of 510 + 384? (a) 700 (b) 900 (c) 1100
  33. 33.Best estimate of 88 × 50? (a) 45000 (b) 450 (c) 4500
  34. 34.Best estimate of 18 × 26? (a) 60 (b) 6000 (c) 600
  35. 35.Best estimate of 735 + 490? (a) 1000 (b) 1400 (c) 1200
  36. 36.Best estimate of 69 × 66? (a) 4900 (b) 49000 (c) 490
  37. 37.Best estimate of 856 + 505? (a) 1400 (b) 1600 (c) 1200
  38. 38.Best estimate of 77 × 71? (a) 56000 (b) 5600 (c) 560
  39. 39.Best estimate of 243 + 599? (a) 800 (b) 600 (c) 1000
  40. 40.Best estimate of 367 + 128? (a) 700 (b) 500 (c) 300

Answer key

  1. 600
  2. 1600
  3. 500
  4. 4900
  5. 1300
  6. 3600
  7. 1000
  8. 500
  9. 1600
  10. 1200
  11. 1100
  12. 500
  13. 3000
  14. 4900
  15. 1100
  16. 1000
  17. 1300
  18. 1500
  19. 1500
  20. 1200
  21. 7000
  22. 1000
  23. 900
  24. 1600
  25. 1100
  26. 400
  27. 400
  28. 7200
  29. 500
  30. 1200
  31. 100
  32. 900
  33. 4500
  34. 600
  35. 1200
  36. 4900
  37. 1400
  38. 5600
  39. 800
  40. 500

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