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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 203 · 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 287 + 609? (a) 1100 (b) 700 (c) 900
  2. 2.Best estimate of 594 + 403? (a) 800 (b) 1200 (c) 1000
  3. 3.Best estimate of 58 × 28? (a) 1800 (b) 18000 (c) 180
  4. 4.Best estimate of 20 × 88? (a) 1800 (b) 180 (c) 18000
  5. 5.Best estimate of 13 × 26? (a) 3000 (b) 30 (c) 300
  6. 6.Best estimate of 16 × 61? (a) 1200 (b) 12000 (c) 120
  7. 7.Best estimate of 303 + 464? (a) 800 (b) 1000 (c) 600
  8. 8.Best estimate of 245 + 149? (a) 100 (b) 500 (c) 300
  9. 9.Best estimate of 428 + 235? (a) 800 (b) 600 (c) 400
  10. 10.Best estimate of 360 + 434? (a) 800 (b) 600 (c) 1000
  11. 11.Best estimate of 81 × 81? (a) 6400 (b) 64000 (c) 640
  12. 12.Best estimate of 147 + 762? (a) 700 (b) 900 (c) 1100
  13. 13.Best estimate of 578 + 800? (a) 1200 (b) 1600 (c) 1400
  14. 14.Best estimate of 14 × 84? (a) 800 (b) 80 (c) 8000
  15. 15.Best estimate of 180 + 289? (a) 500 (b) 700 (c) 300
  16. 16.Best estimate of 824 + 300? (a) 1100 (b) 900 (c) 1300
  17. 17.Best estimate of 705 + 766? (a) 1300 (b) 1700 (c) 1500
  18. 18.Best estimate of 373 + 200? (a) 600 (b) 800 (c) 400
  19. 19.Best estimate of 94 × 21? (a) 18000 (b) 180 (c) 1800
  20. 20.Best estimate of 36 × 97? (a) 400 (b) 4000 (c) 40000
  21. 21.Best estimate of 12 × 34? (a) 300 (b) 30 (c) 3000
  22. 22.Best estimate of 794 + 466? (a) 1500 (b) 1100 (c) 1300
  23. 23.Best estimate of 147 + 696? (a) 600 (b) 1000 (c) 800
  24. 24.Best estimate of 67 × 61? (a) 4200 (b) 420 (c) 42000
  25. 25.Best estimate of 249 + 132? (a) 300 (b) 500 (c) 100
  26. 26.Best estimate of 37 × 22? (a) 800 (b) 8000 (c) 80
  27. 27.Best estimate of 46 × 16? (a) 1000 (b) 100 (c) 10000
  28. 28.Best estimate of 731 + 329? (a) 1200 (b) 800 (c) 1000
  29. 29.Best estimate of 48 × 16? (a) 10000 (b) 1000 (c) 100
  30. 30.Best estimate of 500 + 275? (a) 800 (b) 600 (c) 1000
  31. 31.Best estimate of 34 × 13? (a) 30 (b) 3000 (c) 300
  32. 32.Best estimate of 357 + 524? (a) 700 (b) 900 (c) 1100
  33. 33.Best estimate of 72 × 21? (a) 140 (b) 1400 (c) 14000
  34. 34.Best estimate of 41 × 71? (a) 2800 (b) 280 (c) 28000
  35. 35.Best estimate of 607 + 588? (a) 1200 (b) 1400 (c) 1000
  36. 36.Best estimate of 251 + 726? (a) 1200 (b) 1000 (c) 800
  37. 37.Best estimate of 46 × 84? (a) 40000 (b) 400 (c) 4000
  38. 38.Best estimate of 210 + 165? (a) 400 (b) 600 (c) 200
  39. 39.Best estimate of 603 + 681? (a) 1100 (b) 1500 (c) 1300
  40. 40.Best estimate of 770 + 395? (a) 1400 (b) 1000 (c) 1200

Answer key

  1. 900
  2. 1000
  3. 1800
  4. 1800
  5. 300
  6. 1200
  7. 800
  8. 300
  9. 600
  10. 800
  11. 6400
  12. 900
  13. 1400
  14. 800
  15. 500
  16. 1100
  17. 1500
  18. 600
  19. 1800
  20. 4000
  21. 300
  22. 1300
  23. 800
  24. 4200
  25. 300
  26. 800
  27. 1000
  28. 1000
  29. 1000
  30. 800
  31. 300
  32. 900
  33. 1400
  34. 2800
  35. 1200
  36. 1000
  37. 4000
  38. 400
  39. 1300
  40. 1200

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