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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 590 · 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.Which of these is a perfect cube? (a) 27 (b) 42 (c) 33
  2. 2.What is ∛5832? =
  3. 3.What is ∛15625? =
  4. 4.Which of these is a perfect cube? (a) 169 (b) 125 (c) 144
  5. 5.What is the smallest whole number by which 2 must be divided to get a perfect cube?
  6. 6.Which of these is a perfect cube? (a) 512 (b) 643 (c) 661
  7. 7.What is 2³? =
  8. 8.A cube has a volume of 5832 cubic cm. How long is each edge (in cm)?
  9. 9.What is the smallest whole number by which 81 must be divided to get a perfect cube?
  10. 10.What is ∛64? =
  11. 11.Which of these is a perfect cube? (a) 3811 (b) 3446 (c) 3375
  12. 12.A cube has a volume of 125 cubic cm. How long is each edge (in cm)?
  13. 13.What is 12³? =
  14. 14.A cube has a volume of 4913 cubic cm. How long is each edge (in cm)?
  15. 15.A big cube of edge 10 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  16. 16.Which of these is a perfect cube? (a) 64 (b) 73 (c) 76
  17. 17.A cube has a volume of 8000 cubic cm. How long is each edge (in cm)?
  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.Which of these is a perfect cube? (a) 1170 (b) 1000 (c) 1259
  20. 20.What is the smallest whole number by which 675 must be divided to get a perfect cube?
  21. 21.What is the smallest whole number by which 3 must be divided to get a perfect cube?
  22. 22.A cube has a volume of 2197 cubic cm. How long is each edge (in cm)?
  23. 23.What is the smallest whole number by which 576 must be divided to get a perfect cube?
  24. 24.A big cube of edge 8 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  25. 25.What is the smallest whole number by which 7 must be divided to get a perfect cube?
  26. 26.What is ∛125? =
  27. 27.A cube has a volume of 1000 cubic cm. How long is each edge (in cm)?
  28. 28.What is ∛10648? =
  29. 29.A big cube of edge 8 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  30. 30.A cube has a volume of 1728 cubic cm. How long is each edge (in cm)?
  31. 31.What is 4³? =
  32. 32.A big cube of edge 6 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  33. 33.A big cube of edge 9 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  34. 34.What is the smallest whole number by which 54 must be divided to get a perfect cube?
  35. 35.What is the smallest whole number by which 864 must be divided to get a perfect cube?
  36. 36.What is the smallest whole number by which 24 must be multiplied to get a perfect cube?
  37. 37.What is ∛343? =
  38. 38.What is the smallest whole number by which 448 must be divided to get a perfect cube?
  39. 39.What is the smallest whole number by which 49 must be multiplied to get a perfect cube?
  40. 40.A big cube of edge 24 cm is cut into small cubes of edge 4 cm. How many small cubes are there?

Answer key

  1. 27
  2. 18
  3. 25
  4. 125
  5. 2
  6. 512
  7. 8
  8. 18
  9. 3
  10. 4
  11. 3375
  12. 5
  13. 1728
  14. 17
  15. 125
  16. 64
  17. 20
  18. 27
  19. 1000
  20. 25
  21. 3
  22. 13
  23. 9
  24. 8
  25. 7
  26. 5
  27. 10
  28. 22
  29. 64
  30. 12
  31. 64
  32. 27
  33. 27
  34. 2
  35. 4
  36. 9
  37. 7
  38. 7
  39. 7
  40. 216

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