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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 973 · 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 the smallest whole number by which 5400 must be multiplied to get a perfect cube?
  2. 2.What is the smallest whole number by which 1512 must be multiplied to get a perfect cube?
  3. 3.A big cube of edge 4 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  4. 4.A cube has a volume of 343 cubic cm. How long is each edge (in cm)?
  5. 5.Which of these is a perfect cube? (a) 2895 (b) 3101 (c) 2744
  6. 6.What is the smallest whole number by which 3136 must be divided to get a perfect cube?
  7. 7.A cube has a volume of 512 cubic cm. How long is each edge (in cm)?
  8. 8.What is 6³? =
  9. 9.What is 5³? =
  10. 10.A cube has a volume of 64 cubic cm. How long is each edge (in cm)?
  11. 11.What is 20³? =
  12. 12.What is ∛64? =
  13. 13.A big cube of edge 10 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  14. 14.What is 17³? =
  15. 15.Which of these is a perfect cube? (a) 748 (b) 766 (c) 729
  16. 16.A cube has a volume of 216 cubic cm. How long is each edge (in cm)?
  17. 17.What is ∛125? =
  18. 18.A cube has a volume of 4096 cubic cm. How long is each edge (in cm)?
  19. 19.What is the smallest whole number by which 24 must be divided to get a perfect cube?
  20. 20.What is the smallest whole number by which 320 must be divided to get a perfect cube?
  21. 21.What is the smallest whole number by which 864 must be multiplied to get a perfect cube?
  22. 22.What is ∛13824? =
  23. 23.Which of these is a perfect cube? (a) 1019 (b) 1038 (c) 1000
  24. 24.Which of these is a perfect cube? (a) 1546 (b) 1424 (c) 1331
  25. 25.What is ∛1728? =
  26. 26.A big cube of edge 8 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  27. 27.What is 11³? =
  28. 28.What is the smallest whole number by which 1323 must be divided to get a perfect cube?
  29. 29.A big cube of edge 2 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  30. 30.What is 3³? =
  31. 31.A big cube of edge 12 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  32. 32.What is the smallest whole number by which 16 must be divided to get a perfect cube?
  33. 33.Which of these is a perfect cube? (a) 3375 (b) 3889 (c) 3727
  34. 34.A cube has a volume of 3375 cubic cm. How long is each edge (in cm)?
  35. 35.Which of these is a perfect cube? (a) 49 (b) 27 (c) 51
  36. 36.What is 14³? =
  37. 37.What is 2³? =
  38. 38.What is the smallest whole number by which 392 must be multiplied to get a perfect cube?
  39. 39.What is the smallest whole number by which 128 must be multiplied to get a perfect cube?
  40. 40.A cube has a volume of 1000 cubic cm. How long is each edge (in cm)?

Answer key

  1. 5
  2. 49
  3. 8
  4. 7
  5. 2744
  6. 49
  7. 8
  8. 216
  9. 125
  10. 4
  11. 8000
  12. 4
  13. 125
  14. 4913
  15. 729
  16. 6
  17. 5
  18. 16
  19. 3
  20. 5
  21. 2
  22. 24
  23. 1000
  24. 1331
  25. 12
  26. 64
  27. 1331
  28. 49
  29. 8
  30. 27
  31. 216
  32. 2
  33. 3375
  34. 15
  35. 27
  36. 2744
  37. 8
  38. 7
  39. 4
  40. 10

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