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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 343 · 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 226 + 228? (a) 600 (b) 400 (c) 200
  2. 2.Best estimate of 58 × 32? (a) 1800 (b) 18000 (c) 180
  3. 3.Best estimate of 80 × 22? (a) 16000 (b) 1600 (c) 160
  4. 4.Best estimate of 97 × 44? (a) 400 (b) 4000 (c) 40000
  5. 5.Best estimate of 30 × 48? (a) 1500 (b) 150 (c) 15000
  6. 6.Best estimate of 46 × 36? (a) 20000 (b) 200 (c) 2000
  7. 7.Best estimate of 157 + 638? (a) 800 (b) 1000 (c) 600
  8. 8.Best estimate of 43 × 46? (a) 200 (b) 2000 (c) 20000
  9. 9.Best estimate of 47 × 56? (a) 300 (b) 3000 (c) 30000
  10. 10.Best estimate of 705 + 129? (a) 800 (b) 600 (c) 1000
  11. 11.Best estimate of 44 × 29? (a) 120 (b) 1200 (c) 12000
  12. 12.Best estimate of 62 × 51? (a) 3000 (b) 30000 (c) 300
  13. 13.Best estimate of 97 × 96? (a) 10000 (b) 1000 (c) 100000
  14. 14.Best estimate of 861 + 323? (a) 1000 (b) 1400 (c) 1200
  15. 15.Best estimate of 64 × 59? (a) 3600 (b) 36000 (c) 360
  16. 16.Best estimate of 34 × 17? (a) 6000 (b) 600 (c) 60
  17. 17.Best estimate of 17 × 24? (a) 400 (b) 4000 (c) 40
  18. 18.Best estimate of 97 × 24? (a) 200 (b) 20000 (c) 2000
  19. 19.Best estimate of 76 × 76? (a) 640 (b) 6400 (c) 64000
  20. 20.Best estimate of 456 + 713? (a) 1000 (b) 1400 (c) 1200
  21. 21.Best estimate of 546 + 811? (a) 1100 (b) 1300 (c) 1500
  22. 22.Best estimate of 77 × 33? (a) 2400 (b) 24000 (c) 240
  23. 23.Best estimate of 28 × 13? (a) 300 (b) 30 (c) 3000
  24. 24.Best estimate of 66 × 66? (a) 490 (b) 49000 (c) 4900
  25. 25.Best estimate of 572 + 707? (a) 1500 (b) 1100 (c) 1300
  26. 26.Best estimate of 13 × 92? (a) 900 (b) 9000 (c) 90
  27. 27.Best estimate of 77 × 16? (a) 16000 (b) 1600 (c) 160
  28. 28.Best estimate of 145 + 706? (a) 1000 (b) 800 (c) 600
  29. 29.Best estimate of 38 × 26? (a) 12000 (b) 1200 (c) 120
  30. 30.Best estimate of 486 + 421? (a) 900 (b) 1100 (c) 700
  31. 31.Best estimate of 237 + 865? (a) 1300 (b) 900 (c) 1100
  32. 32.Best estimate of 29 × 41? (a) 1200 (b) 120 (c) 12000
  33. 33.Best estimate of 769 + 237? (a) 1200 (b) 800 (c) 1000
  34. 34.Best estimate of 57 × 64? (a) 3600 (b) 36000 (c) 360
  35. 35.Best estimate of 56 × 18? (a) 12000 (b) 1200 (c) 120
  36. 36.Best estimate of 98 × 14? (a) 10000 (b) 100 (c) 1000
  37. 37.Best estimate of 657 + 540? (a) 1000 (b) 1400 (c) 1200
  38. 38.Best estimate of 507 + 786? (a) 1100 (b) 1500 (c) 1300
  39. 39.Best estimate of 13 × 86? (a) 90 (b) 9000 (c) 900
  40. 40.Best estimate of 491 + 537? (a) 1000 (b) 800 (c) 1200

Answer key

  1. 400
  2. 1800
  3. 1600
  4. 4000
  5. 1500
  6. 2000
  7. 800
  8. 2000
  9. 3000
  10. 800
  11. 1200
  12. 3000
  13. 10000
  14. 1200
  15. 3600
  16. 600
  17. 400
  18. 2000
  19. 6400
  20. 1200
  21. 1300
  22. 2400
  23. 300
  24. 4900
  25. 1300
  26. 900
  27. 1600
  28. 800
  29. 1200
  30. 900
  31. 1100
  32. 1200
  33. 1000
  34. 3600
  35. 1200
  36. 1000
  37. 1200
  38. 1300
  39. 900
  40. 1000

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