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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 352 · 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 192 must be multiplied to get a perfect cube?
  3. 3.What is 17³? =
  4. 4.A cube has a volume of 64 cubic cm. How long is each edge (in cm)?
  5. 5.What is 2³? =
  6. 6.Which of these is a perfect cube? (a) 3667 (b) 3375 (c) 4032
  7. 7.A big cube of edge 24 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  8. 8.A big cube of edge 8 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  9. 9.A big cube of edge 20 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  10. 10.What is the smallest whole number by which 189 must be multiplied to get a perfect cube?
  11. 11.What is 10³? =
  12. 12.What is ∛6859? =
  13. 13.A big cube of edge 5 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  14. 14.Which of these is a perfect cube? (a) 171 (b) 185 (c) 125
  15. 15.What is ∛2744? =
  16. 16.What is 19³? =
  17. 17.Which of these is a perfect cube? (a) 870 (b) 855 (c) 729
  18. 18.Which of these is a perfect cube? (a) 216 (b) 262 (c) 277
  19. 19.Which of these is a perfect cube? (a) 72 (b) 64 (c) 94
  20. 20.A big cube of edge 10 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  21. 21.What is ∛9261? =
  22. 22.What is ∛13824? =
  23. 23.What is 15³? =
  24. 24.Which of these is a perfect cube? (a) 27 (b) 34 (c) 33
  25. 25.What is ∛125? =
  26. 26.What is ∛729? =
  27. 27.A big cube of edge 9 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  28. 28.What is ∛216? =
  29. 29.What is the smallest whole number by which 25 must be multiplied to get a perfect cube?
  30. 30.What is ∛8? =
  31. 31.A cube has a volume of 2197 cubic cm. How long is each edge (in cm)?
  32. 32.A big cube of edge 4 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  33. 33.Which of these is a perfect cube? (a) 1284 (b) 1250 (c) 1000
  34. 34.A cube has a volume of 8 cubic cm. How long is each edge (in cm)?
  35. 35.What is 5³? =
  36. 36.What is the smallest whole number by which 72 must be divided to get a perfect cube?
  37. 37.What is 4³? =
  38. 38.What is the smallest whole number by which 1944 must be multiplied to get a perfect cube?
  39. 39.What is the smallest whole number by which 500 must be multiplied to get a perfect cube?
  40. 40.What is the smallest whole number by which 875 must be multiplied to get a perfect cube?

Answer key

  1. 20
  2. 9
  3. 4913
  4. 4
  5. 8
  6. 3375
  7. 216
  8. 64
  9. 125
  10. 49
  11. 1000
  12. 19
  13. 125
  14. 125
  15. 14
  16. 6859
  17. 729
  18. 216
  19. 64
  20. 125
  21. 21
  22. 24
  23. 3375
  24. 27
  25. 5
  26. 9
  27. 27
  28. 6
  29. 5
  30. 2
  31. 13
  32. 8
  33. 1000
  34. 2
  35. 125
  36. 9
  37. 64
  38. 3
  39. 2
  40. 49

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