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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 248 · 40 sums
TalentJR

The method (Threes make cubes): Cube: n × n × n. Cube root: the number that, used three times, gives the cube. Units digits: 1→1, 2→8, 3→7, 4→4, 5→5, 6→6, 7→3, 8→2, 9→9, 0→0 — use them to guess cube roots. Make a perfect cube: break into primes; multiply by what completes each group of three (or divide by what is left over). A big cube of edge a cut into small cubes of edge b gives (a ÷ b)³ small cubes.

NameDateTime takenScore ___ / 40
  1. 1.What is 5³? =
  2. 2.Which of these is a perfect cube? (a) 64 (b) 66 (c) 78
  3. 3.What is ∛3375? =
  4. 4.Which of these is a perfect cube? (a) 1081 (b) 1000 (c) 1041
  5. 5.What is the smallest whole number by which 392 must be divided to get a perfect cube?
  6. 6.What is ∛6859? =
  7. 7.What is the smallest whole number by which 7 must be divided to get a perfect cube?
  8. 8.What is the smallest whole number by which 625 must be divided to get a perfect cube?
  9. 9.A big cube of edge 12 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  10. 10.What is 18³? =
  11. 11.Which of these is a perfect cube? (a) 253 (b) 216 (c) 322
  12. 12.A cube has a volume of 2744 cubic cm. How long is each edge (in cm)?
  13. 13.What is ∛15625? =
  14. 14.Which of these is a perfect cube? (a) 2495 (b) 2197 (c) 2569
  15. 15.What is ∛1331? =
  16. 16.A big cube of edge 10 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  17. 17.Which of these is a perfect cube? (a) 607 (b) 512 (c) 691
  18. 18.What is ∛343? =
  19. 19.What is 19³? =
  20. 20.What is 15³? =
  21. 21.What is 12³? =
  22. 22.What is ∛1728? =
  23. 23.What is the smallest whole number by which 6125 must be divided to get a perfect cube?
  24. 24.What is 8³? =
  25. 25.A cube has a volume of 6859 cubic cm. How long is each edge (in cm)?
  26. 26.What is the smallest whole number by which 875 must be multiplied to get a perfect cube?
  27. 27.A big cube of edge 16 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  28. 28.Which of these is a perfect cube? (a) 3375 (b) 3788 (c) 4030
  29. 29.What is the smallest whole number by which 108 must be multiplied to get a perfect cube?
  30. 30.What is ∛2744? =
  31. 31.What is ∛9261? =
  32. 32.What is 7³? =
  33. 33.A cube has a volume of 2197 cubic cm. How long is each edge (in cm)?
  34. 34.Which of these is a perfect cube? (a) 2744 (b) 2915 (c) 2811
  35. 35.What is 11³? =
  36. 36.A cube has a volume of 1331 cubic cm. How long is each edge (in cm)?
  37. 37.A cube has a volume of 125 cubic cm. How long is each edge (in cm)?
  38. 38.A cube has a volume of 1728 cubic cm. How long is each edge (in cm)?
  39. 39.A big cube of edge 6 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  40. 40.A big cube of edge 6 cm is cut into small cubes of edge 2 cm. How many small cubes are there?

Answer key

  1. 125
  2. 64
  3. 15
  4. 1000
  5. 49
  6. 19
  7. 7
  8. 5
  9. 216
  10. 5832
  11. 216
  12. 14
  13. 25
  14. 2197
  15. 11
  16. 125
  17. 512
  18. 7
  19. 6859
  20. 3375
  21. 1728
  22. 12
  23. 49
  24. 512
  25. 19
  26. 49
  27. 64
  28. 3375
  29. 2
  30. 14
  31. 21
  32. 343
  33. 13
  34. 2744
  35. 1331
  36. 11
  37. 5
  38. 12
  39. 8
  40. 27

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