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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 713 · 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 349 + 839? (a) 1100 (b) 1300 (c) 900
  2. 2.Best estimate of 27 × 22? (a) 6000 (b) 600 (c) 60
  3. 3.Best estimate of 79 × 96? (a) 8000 (b) 80000 (c) 800
  4. 4.Best estimate of 87 × 51? (a) 450 (b) 45000 (c) 4500
  5. 5.Best estimate of 57 × 26? (a) 1800 (b) 180 (c) 18000
  6. 6.Best estimate of 24 × 56? (a) 1200 (b) 12000 (c) 120
  7. 7.Best estimate of 747 + 344? (a) 800 (b) 1200 (c) 1000
  8. 8.Best estimate of 94 × 12? (a) 90 (b) 900 (c) 9000
  9. 9.Best estimate of 275 + 517? (a) 800 (b) 600 (c) 1000
  10. 10.Best estimate of 38 × 53? (a) 2000 (b) 20000 (c) 200
  11. 11.Best estimate of 53 × 42? (a) 2000 (b) 20000 (c) 200
  12. 12.Best estimate of 56 × 56? (a) 36000 (b) 360 (c) 3600
  13. 13.Best estimate of 22 × 80? (a) 1600 (b) 16000 (c) 160
  14. 14.Best estimate of 593 + 193? (a) 800 (b) 1000 (c) 600
  15. 15.Best estimate of 722 + 635? (a) 1500 (b) 1300 (c) 1100
  16. 16.Best estimate of 125 + 158? (a) 100 (b) 300 (c) 500
  17. 17.Best estimate of 39 × 71? (a) 28000 (b) 2800 (c) 280
  18. 18.Best estimate of 41 × 91? (a) 36000 (b) 360 (c) 3600
  19. 19.Best estimate of 56 × 64? (a) 36000 (b) 360 (c) 3600
  20. 20.Best estimate of 40 × 17? (a) 800 (b) 80 (c) 8000
  21. 21.Best estimate of 251 + 818? (a) 1100 (b) 1300 (c) 900
  22. 22.Best estimate of 225 + 482? (a) 500 (b) 900 (c) 700
  23. 23.Best estimate of 66 × 29? (a) 210 (b) 2100 (c) 21000
  24. 24.Best estimate of 58 × 27? (a) 180 (b) 18000 (c) 1800
  25. 25.Best estimate of 257 + 377? (a) 900 (b) 700 (c) 500
  26. 26.Best estimate of 94 × 20? (a) 18000 (b) 180 (c) 1800
  27. 27.Best estimate of 140 + 772? (a) 700 (b) 1100 (c) 900
  28. 28.Best estimate of 220 + 329? (a) 300 (b) 700 (c) 500
  29. 29.Best estimate of 79 × 38? (a) 3200 (b) 32000 (c) 320
  30. 30.Best estimate of 93 × 64? (a) 540 (b) 5400 (c) 54000
  31. 31.Best estimate of 386 + 776? (a) 1200 (b) 1000 (c) 1400
  32. 32.Best estimate of 19 × 21? (a) 400 (b) 40 (c) 4000
  33. 33.Best estimate of 697 + 308? (a) 1000 (b) 1200 (c) 800
  34. 34.Best estimate of 326 + 585? (a) 1100 (b) 700 (c) 900
  35. 35.Best estimate of 379 + 575? (a) 1200 (b) 800 (c) 1000
  36. 36.Best estimate of 23 × 97? (a) 200 (b) 2000 (c) 20000
  37. 37.Best estimate of 495 + 840? (a) 1100 (b) 1500 (c) 1300
  38. 38.Best estimate of 786 + 251? (a) 1100 (b) 1300 (c) 900
  39. 39.Best estimate of 57 × 83? (a) 480 (b) 4800 (c) 48000
  40. 40.Best estimate of 761 + 683? (a) 1300 (b) 1500 (c) 1700

Answer key

  1. 1100
  2. 600
  3. 8000
  4. 4500
  5. 1800
  6. 1200
  7. 1000
  8. 900
  9. 800
  10. 2000
  11. 2000
  12. 3600
  13. 1600
  14. 800
  15. 1300
  16. 300
  17. 2800
  18. 3600
  19. 3600
  20. 800
  21. 1100
  22. 700
  23. 2100
  24. 1800
  25. 700
  26. 1800
  27. 900
  28. 500
  29. 3200
  30. 5400
  31. 1200
  32. 400
  33. 1000
  34. 900
  35. 1000
  36. 2000
  37. 1300
  38. 1100
  39. 4800
  40. 1500

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