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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 686 · 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 18³? =
  2. 2.What is the smallest whole number by which 7 must be multiplied to get a perfect cube?
  3. 3.A big cube of edge 15 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  4. 4.What is ∛4096? =
  5. 5.What is the smallest whole number by which 25 must be multiplied to get a perfect cube?
  6. 6.What is the smallest whole number by which 54 must be multiplied to get a perfect cube?
  7. 7.A big cube of edge 20 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  8. 8.A big cube of edge 4 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  9. 9.A cube has a volume of 1331 cubic cm. How long is each edge (in cm)?
  10. 10.Which of these is a perfect cube? (a) 2419 (b) 2264 (c) 2197
  11. 11.A big cube of edge 10 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  12. 12.A big cube of edge 24 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  13. 13.What is ∛343? =
  14. 14.What is 15³? =
  15. 15.A cube has a volume of 4913 cubic cm. How long is each edge (in cm)?
  16. 16.What is 7³? =
  17. 17.A big cube of edge 5 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  18. 18.What is ∛27? =
  19. 19.What is the smallest whole number by which 49 must be divided to get a perfect cube?
  20. 20.What is the smallest whole number by which 1600 must be divided to get a perfect cube?
  21. 21.A cube has a volume of 216 cubic cm. How long is each edge (in cm)?
  22. 22.A big cube of edge 6 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  23. 23.What is the smallest whole number by which 40 must be divided to get a perfect cube?
  24. 24.Which of these is a perfect cube? (a) 3528 (b) 3517 (c) 3375
  25. 25.What is 2³? =
  26. 26.A cube has a volume of 2197 cubic cm. How long is each edge (in cm)?
  27. 27.A cube has a volume of 1000 cubic cm. How long is each edge (in cm)?
  28. 28.A big cube of edge 6 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  29. 29.A cube has a volume of 6859 cubic cm. How long is each edge (in cm)?
  30. 30.What is the smallest whole number by which 3 must be divided to get a perfect cube?
  31. 31.What is 9³? =
  32. 32.What is the smallest whole number by which 2 must be multiplied to get a perfect cube?
  33. 33.What is ∛64? =
  34. 34.Which of these is a perfect cube? (a) 2970 (b) 2744 (c) 2846
  35. 35.A cube has a volume of 8 cubic cm. How long is each edge (in cm)?
  36. 36.Which of these is a perfect cube? (a) 53 (b) 33 (c) 27
  37. 37.What is 3³? =
  38. 38.A cube has a volume of 125 cubic cm. How long is each edge (in cm)?
  39. 39.A cube has a volume of 3375 cubic cm. How long is each edge (in cm)?
  40. 40.A cube has a volume of 343 cubic cm. How long is each edge (in cm)?

Answer key

  1. 5832
  2. 49
  3. 125
  4. 16
  5. 5
  6. 4
  7. 125
  8. 64
  9. 11
  10. 2197
  11. 125
  12. 216
  13. 7
  14. 3375
  15. 17
  16. 343
  17. 125
  18. 3
  19. 49
  20. 25
  21. 6
  22. 216
  23. 5
  24. 3375
  25. 8
  26. 13
  27. 10
  28. 27
  29. 19
  30. 3
  31. 729
  32. 4
  33. 4
  34. 2744
  35. 2
  36. 27
  37. 27
  38. 5
  39. 15
  40. 7

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