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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 820 · 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) 160 (b) 180 (c) 125
  2. 2.What is ∛8000? =
  3. 3.Which of these is a perfect cube? (a) 3645 (b) 3658 (c) 3375
  4. 4.Which of these is a perfect cube? (a) 739 (b) 938 (c) 729
  5. 5.A big cube of edge 4 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  6. 6.What is 3³? =
  7. 7.Which of these is a perfect cube? (a) 2244 (b) 2197 (c) 2243
  8. 8.What is 8³? =
  9. 9.A cube has a volume of 5832 cubic cm. How long is each edge (in cm)?
  10. 10.What is ∛512? =
  11. 11.A cube has a volume of 1331 cubic cm. How long is each edge (in cm)?
  12. 12.A cube has a volume of 64 cubic cm. How long is each edge (in cm)?
  13. 13.What is the smallest whole number by which 40 must be divided to get a perfect cube?
  14. 14.What is the smallest whole number by which 4 must be divided to get a perfect cube?
  15. 15.What is the smallest whole number by which 256 must be multiplied to get a perfect cube?
  16. 16.What is ∛1728? =
  17. 17.What is 16³? =
  18. 18.What is ∛4913? =
  19. 19.What is the smallest whole number by which 3 must be multiplied to get a perfect cube?
  20. 20.A cube has a volume of 27 cubic cm. How long is each edge (in cm)?
  21. 21.What is the smallest whole number by which 675 must be multiplied to get a perfect cube?
  22. 22.Which of these is a perfect cube? (a) 3298 (b) 3082 (c) 2744
  23. 23.What is ∛13824? =
  24. 24.What is ∛5832? =
  25. 25.A big cube of edge 8 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  26. 26.What is 12³? =
  27. 27.A cube has a volume of 8000 cubic cm. How long is each edge (in cm)?
  28. 28.A big cube of edge 3 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  29. 29.What is ∛6859? =
  30. 30.What is the smallest whole number by which 49 must be multiplied to get a perfect cube?
  31. 31.What is ∛64? =
  32. 32.Which of these is a perfect cube? (a) 32 (b) 27 (c) 52
  33. 33.What is 7³? =
  34. 34.A big cube of edge 9 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  35. 35.What is the smallest whole number by which 135 must be multiplied to get a perfect cube?
  36. 36.A cube has a volume of 1000 cubic cm. How long is each edge (in cm)?
  37. 37.What is 5³? =
  38. 38.What is ∛9261? =
  39. 39.Which of these is a perfect cube? (a) 1484 (b) 1541 (c) 1331
  40. 40.What is 18³? =

Answer key

  1. 125
  2. 20
  3. 3375
  4. 729
  5. 8
  6. 27
  7. 2197
  8. 512
  9. 18
  10. 8
  11. 11
  12. 4
  13. 5
  14. 4
  15. 2
  16. 12
  17. 4096
  18. 17
  19. 9
  20. 3
  21. 5
  22. 2744
  23. 24
  24. 18
  25. 8
  26. 1728
  27. 20
  28. 27
  29. 19
  30. 7
  31. 4
  32. 27
  33. 343
  34. 27
  35. 25
  36. 10
  37. 125
  38. 21
  39. 1331
  40. 5832

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