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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 716 · 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.A big cube of edge 4 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  2. 2.What is ∛512? =
  3. 3.What is ∛64? =
  4. 4.What is 11³? =
  5. 5.Which of these is a perfect cube? (a) 53 (b) 27 (c) 40
  6. 6.What is the smallest whole number by which 81 must be divided to get a perfect cube?
  7. 7.What is the smallest whole number by which 192 must be divided to get a perfect cube?
  8. 8.Which of these is a perfect cube? (a) 185 (b) 146 (c) 125
  9. 9.What is the smallest whole number by which 32 must be multiplied to get a perfect cube?
  10. 10.What is 7³? =
  11. 11.A big cube of edge 16 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  12. 12.A cube has a volume of 4096 cubic cm. How long is each edge (in cm)?
  13. 13.Which of these is a perfect cube? (a) 1000 (b) 1180 (c) 1072
  14. 14.A cube has a volume of 2744 cubic cm. How long is each edge (in cm)?
  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.What is ∛13824? =
  17. 17.A big cube of edge 3 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  18. 18.What is the smallest whole number by which 500 must be multiplied to get a perfect cube?
  19. 19.Which of these is a perfect cube? (a) 1332 (b) 1416 (c) 1331
  20. 20.A cube has a volume of 1728 cubic cm. How long is each edge (in cm)?
  21. 21.What is the smallest whole number by which 1080 must be multiplied to get a perfect cube?
  22. 22.What is ∛2744? =
  23. 23.A cube has a volume of 27 cubic cm. How long is each edge (in cm)?
  24. 24.What is ∛1728? =
  25. 25.What is the smallest whole number by which 375 must be multiplied to get a perfect cube?
  26. 26.Which of these is a perfect cube? (a) 76 (b) 64 (c) 103
  27. 27.What is the smallest whole number by which 3125 must be divided to get a perfect cube?
  28. 28.A cube has a volume of 216 cubic cm. How long is each edge (in cm)?
  29. 29.What is the smallest whole number by which 5 must be divided to get a perfect cube?
  30. 30.What is the smallest whole number by which 40 must be multiplied to get a perfect cube?
  31. 31.What is 6³? =
  32. 32.What is the smallest whole number by which 54 must be divided to get a perfect cube?
  33. 33.A big cube of edge 5 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  34. 34.What is the smallest whole number by which 256 must be divided to get a perfect cube?
  35. 35.A cube has a volume of 64 cubic cm. How long is each edge (in cm)?
  36. 36.What is the smallest whole number by which 128 must be divided to get a perfect cube?
  37. 37.What is ∛125? =
  38. 38.A big cube of edge 18 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  39. 39.What is ∛3375? =
  40. 40.What is the smallest whole number by which 392 must be multiplied to get a perfect cube?

Answer key

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

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