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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 747 · 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 33 × 32? (a) 900 (b) 9000 (c) 90
  2. 2.Best estimate of 86 × 54? (a) 450 (b) 45000 (c) 4500
  3. 3.Best estimate of 48 × 66? (a) 35000 (b) 3500 (c) 350
  4. 4.Best estimate of 152 + 528? (a) 500 (b) 700 (c) 900
  5. 5.Best estimate of 40 × 92? (a) 3600 (b) 360 (c) 36000
  6. 6.Best estimate of 57 × 12? (a) 6000 (b) 60 (c) 600
  7. 7.Best estimate of 247 + 553? (a) 600 (b) 800 (c) 1000
  8. 8.Best estimate of 452 + 282? (a) 1000 (b) 600 (c) 800
  9. 9.Best estimate of 59 × 39? (a) 240 (b) 24000 (c) 2400
  10. 10.Best estimate of 816 + 135? (a) 900 (b) 700 (c) 1100
  11. 11.Best estimate of 661 + 520? (a) 1200 (b) 1400 (c) 1000
  12. 12.Best estimate of 317 + 785? (a) 1100 (b) 900 (c) 1300
  13. 13.Best estimate of 418 + 864? (a) 1100 (b) 1500 (c) 1300
  14. 14.Best estimate of 86 × 90? (a) 810 (b) 8100 (c) 81000
  15. 15.Best estimate of 36 × 40? (a) 16000 (b) 160 (c) 1600
  16. 16.Best estimate of 97 × 13? (a) 10000 (b) 1000 (c) 100
  17. 17.Best estimate of 694 + 647? (a) 1300 (b) 1500 (c) 1100
  18. 18.Best estimate of 545 + 621? (a) 1300 (b) 1100 (c) 900
  19. 19.Best estimate of 815 + 680? (a) 1300 (b) 1500 (c) 1700
  20. 20.Best estimate of 660 + 313? (a) 800 (b) 1200 (c) 1000
  21. 21.Best estimate of 392 + 448? (a) 1000 (b) 800 (c) 600
  22. 22.Best estimate of 437 + 686? (a) 1100 (b) 900 (c) 1300
  23. 23.Best estimate of 719 + 551? (a) 1300 (b) 1500 (c) 1100
  24. 24.Best estimate of 279 + 131? (a) 400 (b) 200 (c) 600
  25. 25.Best estimate of 308 + 277? (a) 600 (b) 800 (c) 400
  26. 26.Best estimate of 319 + 151? (a) 700 (b) 300 (c) 500
  27. 27.Best estimate of 753 + 153? (a) 1200 (b) 800 (c) 1000
  28. 28.Best estimate of 58 × 70? (a) 4200 (b) 420 (c) 42000
  29. 29.Best estimate of 46 × 87? (a) 4500 (b) 45000 (c) 450
  30. 30.Best estimate of 18 × 30? (a) 600 (b) 6000 (c) 60
  31. 31.Best estimate of 16 × 16? (a) 4000 (b) 40 (c) 400
  32. 32.Best estimate of 36 × 68? (a) 28000 (b) 2800 (c) 280
  33. 33.Best estimate of 291 + 809? (a) 1300 (b) 1100 (c) 900
  34. 34.Best estimate of 867 + 841? (a) 1900 (b) 1700 (c) 1500
  35. 35.Best estimate of 27 × 20? (a) 6000 (b) 600 (c) 60
  36. 36.Best estimate of 611 + 455? (a) 1100 (b) 1300 (c) 900
  37. 37.Best estimate of 64 × 40? (a) 2400 (b) 240 (c) 24000
  38. 38.Best estimate of 64 × 16? (a) 12000 (b) 1200 (c) 120
  39. 39.Best estimate of 76 × 52? (a) 4000 (b) 40000 (c) 400
  40. 40.Best estimate of 94 × 19? (a) 1800 (b) 18000 (c) 180

Answer key

  1. 900
  2. 4500
  3. 3500
  4. 700
  5. 3600
  6. 600
  7. 800
  8. 800
  9. 2400
  10. 900
  11. 1200
  12. 1100
  13. 1300
  14. 8100
  15. 1600
  16. 1000
  17. 1300
  18. 1100
  19. 1500
  20. 1000
  21. 800
  22. 1100
  23. 1300
  24. 400
  25. 600
  26. 500
  27. 1000
  28. 4200
  29. 4500
  30. 600
  31. 400
  32. 2800
  33. 1100
  34. 1700
  35. 600
  36. 1100
  37. 2400
  38. 1200
  39. 4000
  40. 1800

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