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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 978 · 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 66 × 21? (a) 1400 (b) 14000 (c) 140
  2. 2.Best estimate of 26 × 88? (a) 27000 (b) 270 (c) 2700
  3. 3.Best estimate of 16 × 41? (a) 8000 (b) 80 (c) 800
  4. 4.Best estimate of 139 + 324? (a) 200 (b) 400 (c) 600
  5. 5.Best estimate of 20 × 26? (a) 60 (b) 600 (c) 6000
  6. 6.Best estimate of 164 + 418? (a) 400 (b) 800 (c) 600
  7. 7.Best estimate of 37 × 36? (a) 16000 (b) 1600 (c) 160
  8. 8.Best estimate of 18 × 21? (a) 40 (b) 400 (c) 4000
  9. 9.Best estimate of 46 × 39? (a) 2000 (b) 200 (c) 20000
  10. 10.Best estimate of 347 + 316? (a) 600 (b) 800 (c) 400
  11. 11.Best estimate of 26 × 29? (a) 90 (b) 900 (c) 9000
  12. 12.Best estimate of 851 + 169? (a) 900 (b) 1300 (c) 1100
  13. 13.Best estimate of 262 + 594? (a) 1100 (b) 700 (c) 900
  14. 14.Best estimate of 23 × 23? (a) 4000 (b) 40 (c) 400
  15. 15.Best estimate of 64 × 17? (a) 1200 (b) 12000 (c) 120
  16. 16.Best estimate of 73 × 19? (a) 140 (b) 1400 (c) 14000
  17. 17.Best estimate of 72 × 22? (a) 1400 (b) 140 (c) 14000
  18. 18.Best estimate of 339 + 158? (a) 700 (b) 300 (c) 500
  19. 19.Best estimate of 64 × 16? (a) 12000 (b) 1200 (c) 120
  20. 20.Best estimate of 91 × 49? (a) 45000 (b) 450 (c) 4500
  21. 21.Best estimate of 451 + 614? (a) 1300 (b) 900 (c) 1100
  22. 22.Best estimate of 16 × 68? (a) 14000 (b) 140 (c) 1400
  23. 23.Best estimate of 29 × 69? (a) 2100 (b) 21000 (c) 210
  24. 24.Best estimate of 80 × 40? (a) 32000 (b) 3200 (c) 320
  25. 25.Best estimate of 14 × 68? (a) 70 (b) 7000 (c) 700
  26. 26.Best estimate of 308 + 491? (a) 800 (b) 1000 (c) 600
  27. 27.Best estimate of 376 + 270? (a) 500 (b) 700 (c) 900
  28. 28.Best estimate of 627 + 369? (a) 1000 (b) 1200 (c) 800
  29. 29.Best estimate of 83 × 26? (a) 2400 (b) 24000 (c) 240
  30. 30.Best estimate of 878 + 726? (a) 1400 (b) 1800 (c) 1600
  31. 31.Best estimate of 381 + 337? (a) 900 (b) 500 (c) 700
  32. 32.Best estimate of 741 + 562? (a) 1100 (b) 1300 (c) 1500
  33. 33.Best estimate of 36 × 13? (a) 4000 (b) 40 (c) 400
  34. 34.Best estimate of 312 + 202? (a) 500 (b) 700 (c) 300
  35. 35.Best estimate of 431 + 234? (a) 400 (b) 800 (c) 600
  36. 36.Best estimate of 190 + 607? (a) 800 (b) 600 (c) 1000
  37. 37.Best estimate of 251 + 413? (a) 900 (b) 700 (c) 500
  38. 38.Best estimate of 84 × 33? (a) 2400 (b) 24000 (c) 240
  39. 39.Best estimate of 853 + 161? (a) 900 (b) 1300 (c) 1100
  40. 40.Best estimate of 69 × 71? (a) 4900 (b) 490 (c) 49000

Answer key

  1. 1400
  2. 2700
  3. 800
  4. 400
  5. 600
  6. 600
  7. 1600
  8. 400
  9. 2000
  10. 600
  11. 900
  12. 1100
  13. 900
  14. 400
  15. 1200
  16. 1400
  17. 1400
  18. 500
  19. 1200
  20. 4500
  21. 1100
  22. 1400
  23. 2100
  24. 3200
  25. 700
  26. 800
  27. 700
  28. 1000
  29. 2400
  30. 1600
  31. 700
  32. 1300
  33. 400
  34. 500
  35. 600
  36. 800
  37. 700
  38. 2400
  39. 1100
  40. 4900

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