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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 991 · 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 ∛6859? =
  2. 2.What is the smallest whole number by which 7 must be multiplied to get a perfect cube?
  3. 3.A cube has a volume of 1728 cubic cm. How long is each edge (in cm)?
  4. 4.Which of these is a perfect cube? (a) 590 (b) 512 (c) 669
  5. 5.What is ∛2197? =
  6. 6.What is 18³? =
  7. 7.A cube has a volume of 6859 cubic cm. How long is each edge (in cm)?
  8. 8.A cube has a volume of 2744 cubic cm. How long is each edge (in cm)?
  9. 9.What is the smallest whole number by which 1125 must be multiplied to get a perfect cube?
  10. 10.Which of these is a perfect cube? (a) 2080 (b) 2087 (c) 1728
  11. 11.A cube has a volume of 3375 cubic cm. How long is each edge (in cm)?
  12. 12.A cube has a volume of 8000 cubic cm. How long is each edge (in cm)?
  13. 13.Which of these is a perfect cube? (a) 53 (b) 27 (c) 35
  14. 14.What is ∛10648? =
  15. 15.What is 6³? =
  16. 16.Which of these is a perfect cube? (a) 181 (b) 125 (c) 128
  17. 17.A big cube of edge 12 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  18. 18.A cube has a volume of 5832 cubic cm. How long is each edge (in cm)?
  19. 19.What is 12³? =
  20. 20.What is the smallest whole number by which 243 must be multiplied to get a perfect cube?
  21. 21.A big cube of edge 6 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  22. 22.Which of these is a perfect cube? (a) 1202 (b) 1143 (c) 1000
  23. 23.What is ∛4096? =
  24. 24.A cube has a volume of 1331 cubic cm. How long is each edge (in cm)?
  25. 25.What is ∛512? =
  26. 26.Which of these is a perfect cube? (a) 107 (b) 64 (c) 66
  27. 27.What is the smallest whole number by which 16 must be divided to get a perfect cube?
  28. 28.A cube has a volume of 27 cubic cm. How long is each edge (in cm)?
  29. 29.What is ∛2744? =
  30. 30.Which of these is a perfect cube? (a) 251 (b) 216 (c) 284
  31. 31.What is 11³? =
  32. 32.A cube has a volume of 8 cubic cm. How long is each edge (in cm)?
  33. 33.What is the smallest whole number by which 5 must be multiplied to get a perfect cube?
  34. 34.A big cube of edge 9 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 divided to get a perfect cube?
  36. 36.What is ∛15625? =
  37. 37.A big cube of edge 5 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  38. 38.What is ∛27? =
  39. 39.What is ∛1728? =
  40. 40.What is 7³? =

Answer key

  1. 19
  2. 49
  3. 12
  4. 512
  5. 13
  6. 5832
  7. 19
  8. 14
  9. 3
  10. 1728
  11. 15
  12. 20
  13. 27
  14. 22
  15. 216
  16. 125
  17. 216
  18. 18
  19. 1728
  20. 3
  21. 27
  22. 1000
  23. 16
  24. 11
  25. 8
  26. 64
  27. 2
  28. 3
  29. 14
  30. 216
  31. 1331
  32. 2
  33. 25
  34. 27
  35. 2
  36. 25
  37. 125
  38. 3
  39. 12
  40. 343

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