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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 126 · 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 ∛8000? =
  2. 2.What is the smallest whole number by which 40 must be divided to get a perfect cube?
  3. 3.A cube has a volume of 5832 cubic cm. How long is each edge (in cm)?
  4. 4.What is 15³? =
  5. 5.What is the smallest whole number by which 576 must be multiplied to get a perfect cube?
  6. 6.A big cube of edge 20 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  7. 7.A cube has a volume of 343 cubic cm. How long is each edge (in cm)?
  8. 8.A cube has a volume of 125 cubic cm. How long is each edge (in cm)?
  9. 9.What is ∛4096? =
  10. 10.What is the smallest whole number by which 56 must be multiplied to get a perfect cube?
  11. 11.A big cube of edge 8 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  12. 12.What is ∛1331? =
  13. 13.A big cube of edge 9 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  14. 14.What is ∛13824? =
  15. 15.A big cube of edge 24 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  16. 16.Which of these is a perfect cube? (a) 1000 (b) 1264 (c) 1042
  17. 17.Which of these is a perfect cube? (a) 512 (b) 518 (c) 610
  18. 18.What is 13³? =
  19. 19.What is the smallest whole number by which 81 must be divided to get a perfect cube?
  20. 20.What is 8³? =
  21. 21.What is ∛3375? =
  22. 22.Which of these is a perfect cube? (a) 3488 (b) 3375 (c) 3606
  23. 23.A cube has a volume of 4096 cubic cm. How long is each edge (in cm)?
  24. 24.Which of these is a perfect cube? (a) 729 (b) 865 (c) 859
  25. 25.A big cube of edge 12 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  26. 26.What is ∛2197? =
  27. 27.What is the smallest whole number by which 432 must be divided to get a perfect cube?
  28. 28.What is the smallest whole number by which 5 must be divided to get a perfect cube?
  29. 29.Which of these is a perfect cube? (a) 43 (b) 27 (c) 49
  30. 30.Which of these is a perfect cube? (a) 1522 (b) 1345 (c) 1331
  31. 31.A big cube of edge 4 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  32. 32.A cube has a volume of 1331 cubic cm. How long is each edge (in cm)?
  33. 33.What is 20³? =
  34. 34.What is 3³? =
  35. 35.Which of these is a perfect cube? (a) 230 (b) 226 (c) 216
  36. 36.What is ∛8? =
  37. 37.A cube has a volume of 3375 cubic cm. How long is each edge (in cm)?
  38. 38.What is 14³? =
  39. 39.A big cube of edge 12 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  40. 40.What is 4³? =

Answer key

  1. 20
  2. 5
  3. 18
  4. 3375
  5. 3
  6. 125
  7. 7
  8. 5
  9. 16
  10. 49
  11. 8
  12. 11
  13. 27
  14. 24
  15. 216
  16. 1000
  17. 512
  18. 2197
  19. 3
  20. 512
  21. 15
  22. 3375
  23. 16
  24. 729
  25. 216
  26. 13
  27. 2
  28. 5
  29. 27
  30. 1331
  31. 8
  32. 11
  33. 8000
  34. 27
  35. 216
  36. 2
  37. 15
  38. 2744
  39. 27
  40. 64

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