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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 894 · 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 20³? =
  2. 2.Which of these is a perfect cube? (a) 139 (b) 125 (c) 146
  3. 3.What is 9³? =
  4. 4.What is the smallest whole number by which 256 must be multiplied to get a perfect cube?
  5. 5.What is 16³? =
  6. 6.What is the smallest whole number by which 320 must be divided to get a perfect cube?
  7. 7.A big cube of edge 2 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  8. 8.Which of these is a perfect cube? (a) 674 (b) 524 (c) 512
  9. 9.What is the smallest whole number by which 200 must be divided to get a perfect cube?
  10. 10.What is ∛8? =
  11. 11.What is the smallest whole number by which 1080 must be multiplied to get a perfect cube?
  12. 12.A big cube of edge 4 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  13. 13.What is the smallest whole number by which 16 must be divided to get a perfect cube?
  14. 14.Which of these is a perfect cube? (a) 64 (b) 74 (c) 79
  15. 15.What is the smallest whole number by which 128 must be divided to get a perfect cube?
  16. 16.Which of these is a perfect cube? (a) 2744 (b) 2983 (c) 2831
  17. 17.A cube has a volume of 512 cubic cm. How long is each edge (in cm)?
  18. 18.What is ∛12167? =
  19. 19.A big cube of edge 18 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  20. 20.What is ∛125? =
  21. 21.What is ∛216? =
  22. 22.A cube has a volume of 1728 cubic cm. How long is each edge (in cm)?
  23. 23.A cube has a volume of 5832 cubic cm. How long is each edge (in cm)?
  24. 24.Which of these is a perfect cube? (a) 2667 (b) 2197 (c) 2295
  25. 25.A cube has a volume of 125 cubic cm. How long is each edge (in cm)?
  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 2744 cubic cm. How long is each edge (in cm)?
  28. 28.A cube has a volume of 8 cubic cm. How long is each edge (in cm)?
  29. 29.What is ∛64? =
  30. 30.What is the smallest whole number by which 432 must be multiplied to get a perfect cube?
  31. 31.What is the smallest whole number by which 500 must be multiplied to get a perfect cube?
  32. 32.What is the smallest whole number by which 5 must be divided to get a perfect cube?
  33. 33.What is 5³? =
  34. 34.What is the smallest whole number by which 500 must be divided to get a perfect cube?
  35. 35.What is 10³? =
  36. 36.A big cube of edge 5 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  37. 37.A cube has a volume of 1331 cubic cm. How long is each edge (in cm)?
  38. 38.What is ∛9261? =
  39. 39.What is ∛4096? =
  40. 40.Which of these is a perfect cube? (a) 1846 (b) 1827 (c) 1728

Answer key

  1. 8000
  2. 125
  3. 729
  4. 2
  5. 4096
  6. 5
  7. 8
  8. 512
  9. 25
  10. 2
  11. 25
  12. 64
  13. 2
  14. 64
  15. 2
  16. 2744
  17. 8
  18. 23
  19. 216
  20. 5
  21. 6
  22. 12
  23. 18
  24. 2197
  25. 5
  26. 13
  27. 14
  28. 2
  29. 4
  30. 4
  31. 2
  32. 5
  33. 125
  34. 4
  35. 1000
  36. 125
  37. 11
  38. 21
  39. 16
  40. 1728

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