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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 473 · 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) 280 (b) 216 (c) 248
  2. 2.Which of these is a perfect cube? (a) 2247 (b) 2668 (c) 2197
  3. 3.A big cube of edge 4 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  4. 4.What is ∛8000? =
  5. 5.A big cube of edge 5 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  6. 6.Which of these is a perfect cube? (a) 407 (b) 480 (c) 343
  7. 7.A cube has a volume of 8000 cubic cm. How long is each edge (in cm)?
  8. 8.A big cube of edge 20 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  9. 9.A cube has a volume of 3375 cubic cm. How long is each edge (in cm)?
  10. 10.What is the smallest whole number by which 24 must be divided to get a perfect cube?
  11. 11.What is the smallest whole number by which 875 must be divided to get a perfect cube?
  12. 12.A big cube of edge 18 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  13. 13.Which of these is a perfect cube? (a) 135 (b) 146 (c) 125
  14. 14.What is the smallest whole number by which 1125 must be multiplied to get a perfect cube?
  15. 15.What is 4³? =
  16. 16.What is the smallest whole number by which 256 must be multiplied to get a perfect cube?
  17. 17.Which of these is a perfect cube? (a) 863 (b) 753 (c) 729
  18. 18.What is the smallest whole number by which 200 must be multiplied to get a perfect cube?
  19. 19.What is ∛125? =
  20. 20.Which of these is a perfect cube? (a) 67 (b) 64 (c) 95
  21. 21.What is 8³? =
  22. 22.A big cube of edge 8 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  23. 23.A big cube of edge 12 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  24. 24.What is the smallest whole number by which 500 must be multiplied to get a perfect cube?
  25. 25.What is 15³? =
  26. 26.A big cube of edge 6 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  27. 27.Which of these is a perfect cube? (a) 29 (b) 35 (c) 27
  28. 28.What is 13³? =
  29. 29.A big cube of edge 4 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  30. 30.A big cube of edge 9 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  31. 31.What is the smallest whole number by which 49 must be divided to get a perfect cube?
  32. 32.What is 3³? =
  33. 33.A cube has a volume of 8 cubic cm. How long is each edge (in cm)?
  34. 34.A big cube of edge 15 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  35. 35.What is the smallest whole number by which 432 must be multiplied to get a perfect cube?
  36. 36.What is the smallest whole number by which 16 must be divided to get a perfect cube?
  37. 37.What is 19³? =
  38. 38.What is 12³? =
  39. 39.What is ∛2197? =
  40. 40.What is the smallest whole number by which 1125 must be divided to get a perfect cube?

Answer key

  1. 216
  2. 2197
  3. 64
  4. 20
  5. 125
  6. 343
  7. 20
  8. 125
  9. 15
  10. 3
  11. 7
  12. 216
  13. 125
  14. 3
  15. 64
  16. 2
  17. 729
  18. 5
  19. 5
  20. 64
  21. 512
  22. 8
  23. 216
  24. 2
  25. 3375
  26. 216
  27. 27
  28. 2197
  29. 8
  30. 27
  31. 49
  32. 27
  33. 2
  34. 125
  35. 4
  36. 2
  37. 6859
  38. 1728
  39. 13
  40. 9

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