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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 876 · 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 11³? =
  2. 2.What is 2³? =
  3. 3.What is the smallest whole number by which 10584 must be divided to get a perfect cube?
  4. 4.What is 7³? =
  5. 5.What is ∛8? =
  6. 6.A big cube of edge 6 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  7. 7.Which of these is a perfect cube? (a) 2197 (b) 2305 (c) 2620
  8. 8.Which of these is a perfect cube? (a) 42 (b) 27 (c) 36
  9. 9.A big cube of edge 9 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  10. 10.Which of these is a perfect cube? (a) 1339 (b) 1344 (c) 1331
  11. 11.Which of these is a perfect cube? (a) 250 (b) 231 (c) 216
  12. 12.A cube has a volume of 4096 cubic cm. How long is each edge (in cm)?
  13. 13.A cube has a volume of 3375 cubic cm. How long is each edge (in cm)?
  14. 14.A cube has a volume of 216 cubic cm. How long is each edge (in cm)?
  15. 15.What is 10³? =
  16. 16.A cube has a volume of 2744 cubic cm. How long is each edge (in cm)?
  17. 17.A big cube of edge 18 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  18. 18.A big cube of edge 12 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  19. 19.A cube has a volume of 27 cubic cm. How long is each edge (in cm)?
  20. 20.What is 5³? =
  21. 21.What is the smallest whole number by which 81 must be multiplied to get a perfect cube?
  22. 22.What is ∛64? =
  23. 23.A big cube of edge 8 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  24. 24.Which of these is a perfect cube? (a) 140 (b) 165 (c) 125
  25. 25.A cube has a volume of 125 cubic cm. How long is each edge (in cm)?
  26. 26.What is 6³? =
  27. 27.What is the smallest whole number by which 32 must be multiplied to get a perfect cube?
  28. 28.What is 17³? =
  29. 29.What is 8³? =
  30. 30.What is ∛27? =
  31. 31.What is the smallest whole number by which 1080 must be multiplied to get a perfect cube?
  32. 32.Which of these is a perfect cube? (a) 729 (b) 785 (c) 953
  33. 33.A big cube of edge 2 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  34. 34.What is ∛1728? =
  35. 35.What is 9³? =
  36. 36.What is the smallest whole number by which 448 must be multiplied to get a perfect cube?
  37. 37.What is ∛343? =
  38. 38.A big cube of edge 4 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  39. 39.A big cube of edge 6 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  40. 40.What is the smallest whole number by which 243 must be multiplied to get a perfect cube?

Answer key

  1. 1331
  2. 8
  3. 49
  4. 343
  5. 2
  6. 27
  7. 2197
  8. 27
  9. 27
  10. 1331
  11. 216
  12. 16
  13. 15
  14. 6
  15. 1000
  16. 14
  17. 216
  18. 27
  19. 3
  20. 125
  21. 9
  22. 4
  23. 8
  24. 125
  25. 5
  26. 216
  27. 2
  28. 4913
  29. 512
  30. 3
  31. 25
  32. 729
  33. 8
  34. 12
  35. 729
  36. 49
  37. 7
  38. 64
  39. 8
  40. 3

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