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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 183 · 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 47 × 68? (a) 3500 (b) 35000 (c) 350
  2. 2.Best estimate of 84 × 49? (a) 400 (b) 40000 (c) 4000
  3. 3.Best estimate of 743 + 158? (a) 700 (b) 900 (c) 1100
  4. 4.Best estimate of 19 × 93? (a) 180 (b) 1800 (c) 18000
  5. 5.Best estimate of 36 × 20? (a) 800 (b) 80 (c) 8000
  6. 6.Best estimate of 41 × 74? (a) 28000 (b) 280 (c) 2800
  7. 7.Best estimate of 503 + 137? (a) 400 (b) 600 (c) 800
  8. 8.Best estimate of 759 + 657? (a) 1500 (b) 1700 (c) 1300
  9. 9.Best estimate of 36 × 52? (a) 200 (b) 20000 (c) 2000
  10. 10.Best estimate of 50 × 36? (a) 20000 (b) 200 (c) 2000
  11. 11.Best estimate of 777 + 302? (a) 900 (b) 1300 (c) 1100
  12. 12.Best estimate of 12 × 51? (a) 500 (b) 5000 (c) 50
  13. 13.Best estimate of 359 + 604? (a) 1000 (b) 800 (c) 1200
  14. 14.Best estimate of 36 × 76? (a) 32000 (b) 3200 (c) 320
  15. 15.Best estimate of 60 × 14? (a) 60 (b) 600 (c) 6000
  16. 16.Best estimate of 732 + 590? (a) 1300 (b) 1100 (c) 1500
  17. 17.Best estimate of 28 × 30? (a) 9000 (b) 900 (c) 90
  18. 18.Best estimate of 123 + 580? (a) 500 (b) 900 (c) 700
  19. 19.Best estimate of 23 × 46? (a) 10000 (b) 1000 (c) 100
  20. 20.Best estimate of 382 + 745? (a) 900 (b) 1100 (c) 1300
  21. 21.Best estimate of 26 × 16? (a) 60 (b) 600 (c) 6000
  22. 22.Best estimate of 16 × 73? (a) 140 (b) 14000 (c) 1400
  23. 23.Best estimate of 76 × 92? (a) 720 (b) 72000 (c) 7200
  24. 24.Best estimate of 454 + 608? (a) 1300 (b) 1100 (c) 900
  25. 25.Best estimate of 334 + 690? (a) 1200 (b) 1000 (c) 800
  26. 26.Best estimate of 69 × 53? (a) 3500 (b) 35000 (c) 350
  27. 27.Best estimate of 208 + 355? (a) 800 (b) 600 (c) 400
  28. 28.Best estimate of 274 + 325? (a) 800 (b) 400 (c) 600
  29. 29.Best estimate of 77 × 62? (a) 48000 (b) 480 (c) 4800
  30. 30.Best estimate of 39 × 18? (a) 800 (b) 8000 (c) 80
  31. 31.Best estimate of 47 × 18? (a) 1000 (b) 10000 (c) 100
  32. 32.Best estimate of 412 + 575? (a) 1200 (b) 800 (c) 1000
  33. 33.Best estimate of 156 + 724? (a) 1100 (b) 900 (c) 700
  34. 34.Best estimate of 486 + 551? (a) 900 (b) 1300 (c) 1100
  35. 35.Best estimate of 754 + 820? (a) 1800 (b) 1400 (c) 1600
  36. 36.Best estimate of 253 + 305? (a) 400 (b) 600 (c) 800
  37. 37.Best estimate of 64 × 56? (a) 36000 (b) 360 (c) 3600
  38. 38.Best estimate of 841 + 211? (a) 1200 (b) 1000 (c) 800
  39. 39.Best estimate of 536 + 201? (a) 700 (b) 500 (c) 900
  40. 40.Best estimate of 149 + 722? (a) 1000 (b) 600 (c) 800

Answer key

  1. 3500
  2. 4000
  3. 900
  4. 1800
  5. 800
  6. 2800
  7. 600
  8. 1500
  9. 2000
  10. 2000
  11. 1100
  12. 500
  13. 1000
  14. 3200
  15. 600
  16. 1300
  17. 900
  18. 700
  19. 1000
  20. 1100
  21. 600
  22. 1400
  23. 7200
  24. 1100
  25. 1000
  26. 3500
  27. 600
  28. 600
  29. 4800
  30. 800
  31. 1000
  32. 1000
  33. 900
  34. 1100
  35. 1600
  36. 600
  37. 3600
  38. 1000
  39. 700
  40. 800

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