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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 771 · 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 6³? =
  2. 2.What is 7³? =
  3. 3.What is ∛8? =
  4. 4.Which of these is a perfect cube? (a) 3518 (b) 3375 (c) 3550
  5. 5.What is the smallest whole number by which 2 must be divided to get a perfect cube?
  6. 6.What is the smallest whole number by which 200 must be multiplied to get a perfect cube?
  7. 7.What is 14³? =
  8. 8.What is ∛9261? =
  9. 9.What is 8³? =
  10. 10.What is 11³? =
  11. 11.A big cube of edge 2 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  12. 12.What is 5³? =
  13. 13.What is 10³? =
  14. 14.What is ∛15625? =
  15. 15.What is 3³? =
  16. 16.A big cube of edge 3 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  17. 17.What is ∛2197? =
  18. 18.Which of these is a perfect cube? (a) 97 (b) 83 (c) 64
  19. 19.Which of these is a perfect cube? (a) 1000 (b) 1221 (c) 1154
  20. 20.What is the smallest whole number by which 192 must be multiplied to get a perfect cube?
  21. 21.What is the smallest whole number by which 128 must be divided to get a perfect cube?
  22. 22.What is 4³? =
  23. 23.What is the smallest whole number by which 1125 must be multiplied to get a perfect cube?
  24. 24.Which of these is a perfect cube? (a) 2826 (b) 2783 (c) 2744
  25. 25.What is ∛5832? =
  26. 26.A cube has a volume of 216 cubic cm. How long is each edge (in cm)?
  27. 27.A cube has a volume of 8 cubic cm. How long is each edge (in cm)?
  28. 28.What is 20³? =
  29. 29.Which of these is a perfect cube? (a) 514 (b) 524 (c) 512
  30. 30.What is ∛13824? =
  31. 31.What is ∛1000? =
  32. 32.What is the smallest whole number by which 1512 must be multiplied to get a perfect cube?
  33. 33.What is ∛1728? =
  34. 34.What is ∛6859? =
  35. 35.A cube has a volume of 512 cubic cm. How long is each edge (in cm)?
  36. 36.Which of these is a perfect cube? (a) 216 (b) 315 (c) 316
  37. 37.What is the smallest whole number by which 432 must be divided to get a perfect cube?
  38. 38.What is the smallest whole number by which 1600 must be multiplied to get a perfect cube?
  39. 39.What is the smallest whole number by which 3 must be multiplied to get a perfect cube?
  40. 40.A big cube of edge 15 cm is cut into small cubes of edge 3 cm. How many small cubes are there?

Answer key

  1. 216
  2. 343
  3. 2
  4. 3375
  5. 2
  6. 5
  7. 2744
  8. 21
  9. 512
  10. 1331
  11. 8
  12. 125
  13. 1000
  14. 25
  15. 27
  16. 27
  17. 13
  18. 64
  19. 1000
  20. 9
  21. 2
  22. 64
  23. 3
  24. 2744
  25. 18
  26. 6
  27. 2
  28. 8000
  29. 512
  30. 24
  31. 10
  32. 49
  33. 12
  34. 19
  35. 8
  36. 216
  37. 2
  38. 5
  39. 9
  40. 125

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