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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 440 · 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 13³? =
  2. 2.What is 7³? =
  3. 3.What is ∛5832? =
  4. 4.A cube has a volume of 4913 cubic cm. How long is each edge (in cm)?
  5. 5.What is the smallest whole number by which 3 must be divided to get a perfect cube?
  6. 6.A cube has a volume of 27 cubic cm. How long is each edge (in cm)?
  7. 7.A cube has a volume of 8000 cubic cm. How long is each edge (in cm)?
  8. 8.What is ∛2744? =
  9. 9.A big cube of edge 6 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) 79 (b) 98 (c) 64
  11. 11.What is ∛216? =
  12. 12.Which of these is a perfect cube? (a) 45 (b) 35 (c) 27
  13. 13.A big cube of edge 20 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  14. 14.What is ∛9261? =
  15. 15.A big cube of edge 15 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  16. 16.What is 16³? =
  17. 17.Which of these is a perfect cube? (a) 2668 (b) 2698 (c) 2197
  18. 18.Which of these is a perfect cube? (a) 520 (b) 512 (c) 647
  19. 19.What is 15³? =
  20. 20.A cube has a volume of 216 cubic cm. How long is each edge (in cm)?
  21. 21.A big cube of edge 12 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  22. 22.What is 12³? =
  23. 23.What is ∛343? =
  24. 24.A cube has a volume of 64 cubic cm. How long is each edge (in cm)?
  25. 25.What is the smallest whole number by which 1600 must be multiplied to get a perfect cube?
  26. 26.A big cube of edge 12 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  27. 27.Which of these is a perfect cube? (a) 125 (b) 150 (c) 170
  28. 28.A big cube of edge 12 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  29. 29.What is the smallest whole number by which 7 must be divided to get a perfect cube?
  30. 30.What is ∛27? =
  31. 31.What is the smallest whole number by which 16 must be multiplied to get a perfect cube?
  32. 32.What is ∛512? =
  33. 33.What is the smallest whole number by which 320 must be divided to get a perfect cube?
  34. 34.What is the smallest whole number by which 9 must be divided to get a perfect cube?
  35. 35.What is the smallest whole number by which 1125 must be multiplied to get a perfect cube?
  36. 36.A big cube of edge 6 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  37. 37.What is 6³? =
  38. 38.A big cube of edge 3 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  39. 39.Which of these is a perfect cube? (a) 1728 (b) 1767 (c) 2121
  40. 40.What is ∛2197? =

Answer key

  1. 2197
  2. 343
  3. 18
  4. 17
  5. 3
  6. 3
  7. 20
  8. 14
  9. 8
  10. 64
  11. 6
  12. 27
  13. 125
  14. 21
  15. 125
  16. 4096
  17. 2197
  18. 512
  19. 3375
  20. 6
  21. 64
  22. 1728
  23. 7
  24. 4
  25. 5
  26. 216
  27. 125
  28. 27
  29. 7
  30. 3
  31. 4
  32. 8
  33. 5
  34. 9
  35. 3
  36. 27
  37. 216
  38. 27
  39. 1728
  40. 13

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