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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 72 · 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.A big cube of edge 8 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  2. 2.What is ∛729? =
  3. 3.What is the smallest whole number by which 375 must be multiplied to get a perfect cube?
  4. 4.What is the smallest whole number by which 256 must be multiplied to get a perfect cube?
  5. 5.What is the smallest whole number by which 1080 must be divided to get a perfect cube?
  6. 6.What is the smallest whole number by which 432 must be divided to get a perfect cube?
  7. 7.Which of these is a perfect cube? (a) 2744 (b) 3066 (c) 3042
  8. 8.What is the smallest whole number by which 648 must be multiplied to get a perfect cube?
  9. 9.What is 2³? =
  10. 10.What is the smallest whole number by which 3136 must be divided to get a perfect cube?
  11. 11.What is the smallest whole number by which 10584 must be multiplied to get a perfect cube?
  12. 12.What is the smallest whole number by which 3 must be multiplied to get a perfect cube?
  13. 13.What is 6³? =
  14. 14.What is the smallest whole number by which 625 must be divided to get a perfect cube?
  15. 15.What is 19³? =
  16. 16.What is ∛15625? =
  17. 17.A cube has a volume of 27 cubic cm. How long is each edge (in cm)?
  18. 18.Which of these is a perfect cube? (a) 454 (b) 389 (c) 343
  19. 19.What is ∛5832? =
  20. 20.Which of these is a perfect cube? (a) 2053 (b) 2048 (c) 1728
  21. 21.What is the smallest whole number by which 375 must be divided to get a perfect cube?
  22. 22.A cube has a volume of 8000 cubic cm. How long is each edge (in cm)?
  23. 23.Which of these is a perfect cube? (a) 64 (b) 97 (c) 91
  24. 24.What is ∛4096? =
  25. 25.Which of these is a perfect cube? (a) 683 (b) 553 (c) 512
  26. 26.A cube has a volume of 3375 cubic cm. How long is each edge (in cm)?
  27. 27.What is the smallest whole number by which 500 must be multiplied to get a perfect cube?
  28. 28.A big cube of edge 6 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  29. 29.What is 15³? =
  30. 30.What is ∛512? =
  31. 31.What is 5³? =
  32. 32.What is ∛9261? =
  33. 33.What is the smallest whole number by which 448 must be divided to get a perfect cube?
  34. 34.A big cube of edge 4 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  35. 35.A cube has a volume of 8 cubic cm. How long is each edge (in cm)?
  36. 36.What is the smallest whole number by which 56 must be multiplied to get a perfect cube?
  37. 37.What is ∛8000? =
  38. 38.What is 8³? =
  39. 39.What is the smallest whole number by which 320 must be divided to get a perfect cube?
  40. 40.What is 7³? =

Answer key

  1. 8
  2. 9
  3. 9
  4. 2
  5. 5
  6. 2
  7. 2744
  8. 9
  9. 8
  10. 49
  11. 7
  12. 9
  13. 216
  14. 5
  15. 6859
  16. 25
  17. 3
  18. 343
  19. 18
  20. 1728
  21. 3
  22. 20
  23. 64
  24. 16
  25. 512
  26. 15
  27. 2
  28. 27
  29. 3375
  30. 8
  31. 125
  32. 21
  33. 7
  34. 8
  35. 2
  36. 49
  37. 20
  38. 512
  39. 5
  40. 343

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