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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 651 · 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.Which of these is a perfect cube? (a) 2761 (b) 3111 (c) 2744
  2. 2.What is the smallest whole number by which 16 must be multiplied to get a perfect cube?
  3. 3.What is ∛13824? =
  4. 4.A cube has a volume of 1728 cubic cm. How long is each edge (in cm)?
  5. 5.A big cube of edge 6 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  6. 6.A big cube of edge 18 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  7. 7.A big cube of edge 4 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  8. 8.What is ∛15625? =
  9. 9.What is the smallest whole number by which 16 must be divided to get a perfect cube?
  10. 10.What is ∛64? =
  11. 11.What is the smallest whole number by which 189 must be divided to get a perfect cube?
  12. 12.What is the smallest whole number by which 32 must be divided to get a perfect cube?
  13. 13.What is ∛10648? =
  14. 14.A big cube of edge 12 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  15. 15.A cube has a volume of 5832 cubic cm. How long is each edge (in cm)?
  16. 16.A cube has a volume of 729 cubic cm. How long is each edge (in cm)?
  17. 17.What is ∛1331? =
  18. 18.Which of these is a perfect cube? (a) 286 (b) 216 (c) 219
  19. 19.A cube has a volume of 6859 cubic cm. How long is each edge (in cm)?
  20. 20.A cube has a volume of 8 cubic cm. How long is each edge (in cm)?
  21. 21.What is the smallest whole number by which 2 must be divided to get a perfect cube?
  22. 22.A cube has a volume of 64 cubic cm. How long is each edge (in cm)?
  23. 23.Which of these is a perfect cube? (a) 95 (b) 64 (c) 74
  24. 24.What is 18³? =
  25. 25.A cube has a volume of 512 cubic cm. How long is each edge (in cm)?
  26. 26.Which of these is a perfect cube? (a) 2669 (b) 2197 (c) 2421
  27. 27.What is the smallest whole number by which 320 must be multiplied to get a perfect cube?
  28. 28.A big cube of edge 10 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  29. 29.What is 7³? =
  30. 30.What is the smallest whole number by which 1512 must be multiplied to get a perfect cube?
  31. 31.What is the smallest whole number by which 81 must be divided to get a perfect cube?
  32. 32.What is ∛125? =
  33. 33.A big cube of edge 3 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  34. 34.A cube has a volume of 8000 cubic cm. How long is each edge (in cm)?
  35. 35.What is the smallest whole number by which 6125 must be multiplied to get a perfect cube?
  36. 36.A big cube of edge 4 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  37. 37.What is 6³? =
  38. 38.What is ∛6859? =
  39. 39.What is the smallest whole number by which 25 must be multiplied to get a perfect cube?
  40. 40.What is 10³? =

Answer key

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

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