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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 855 · 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 ∛512? =
  2. 2.What is ∛9261? =
  3. 3.A big cube of edge 18 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  4. 4.What is the smallest whole number by which 25 must be divided to get a perfect cube?
  5. 5.What is ∛1000? =
  6. 6.Which of these is a perfect cube? (a) 156 (b) 125 (c) 162
  7. 7.A cube has a volume of 1728 cubic cm. How long is each edge (in cm)?
  8. 8.What is 14³? =
  9. 9.What is 5³? =
  10. 10.A big cube of edge 9 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  11. 11.What is ∛125? =
  12. 12.Which of these is a perfect cube? (a) 1172 (b) 1000 (c) 1185
  13. 13.What is ∛216? =
  14. 14.Which of these is a perfect cube? (a) 1331 (b) 1538 (c) 1633
  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.What is the smallest whole number by which 192 must be multiplied to get a perfect cube?
  17. 17.What is ∛27? =
  18. 18.Which of these is a perfect cube? (a) 79 (b) 78 (c) 64
  19. 19.What is the smallest whole number by which 40 must be multiplied to get a perfect cube?
  20. 20.Which of these is a perfect cube? (a) 3775 (b) 4026 (c) 3375
  21. 21.A cube has a volume of 1331 cubic cm. How long is each edge (in cm)?
  22. 22.What is the smallest whole number by which 2 must be multiplied to get a perfect cube?
  23. 23.What is 13³? =
  24. 24.What is the smallest whole number by which 54 must be divided to get a perfect cube?
  25. 25.What is ∛2744? =
  26. 26.What is 20³? =
  27. 27.A big cube of edge 8 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  28. 28.A cube has a volume of 729 cubic cm. How long is each edge (in cm)?
  29. 29.What is the smallest whole number by which 875 must be divided to get a perfect cube?
  30. 30.Which of these is a perfect cube? (a) 232 (b) 279 (c) 216
  31. 31.A cube has a volume of 27 cubic cm. How long is each edge (in cm)?
  32. 32.What is ∛5832? =
  33. 33.Which of these is a perfect cube? (a) 1728 (b) 1911 (c) 2124
  34. 34.What is 6³? =
  35. 35.What is the smallest whole number by which 1944 must be divided to get a perfect cube?
  36. 36.A cube has a volume of 8 cubic cm. How long is each edge (in cm)?
  37. 37.What is 9³? =
  38. 38.What is 2³? =
  39. 39.What is ∛729? =
  40. 40.What is 10³? =

Answer key

  1. 8
  2. 21
  3. 216
  4. 25
  5. 10
  6. 125
  7. 12
  8. 2744
  9. 125
  10. 27
  11. 5
  12. 1000
  13. 6
  14. 1331
  15. 125
  16. 9
  17. 3
  18. 64
  19. 25
  20. 3375
  21. 11
  22. 4
  23. 2197
  24. 2
  25. 14
  26. 8000
  27. 8
  28. 9
  29. 7
  30. 216
  31. 3
  32. 18
  33. 1728
  34. 216
  35. 9
  36. 2
  37. 729
  38. 8
  39. 9
  40. 1000

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