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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 550 · 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 ∛5832? =
  2. 2.What is the smallest whole number by which 875 must be multiplied to get a perfect cube?
  3. 3.What is the smallest whole number by which 10584 must be multiplied to get a perfect cube?
  4. 4.Which of these is a perfect cube? (a) 1777 (b) 2026 (c) 1728
  5. 5.A cube has a volume of 64 cubic cm. How long is each edge (in cm)?
  6. 6.Which of these is a perfect cube? (a) 1000 (b) 1210 (c) 1211
  7. 7.What is 17³? =
  8. 8.What is ∛15625? =
  9. 9.A big cube of edge 12 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  10. 10.A big cube of edge 6 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  11. 11.What is the smallest whole number by which 432 must be divided to get a perfect cube?
  12. 12.Which of these is a perfect cube? (a) 3004 (b) 2744 (c) 3136
  13. 13.What is the smallest whole number by which 250 must be divided to get a perfect cube?
  14. 14.Which of these is a perfect cube? (a) 29 (b) 27 (c) 49
  15. 15.What is the smallest whole number by which 243 must be divided to get a perfect cube?
  16. 16.A cube has a volume of 8 cubic cm. How long is each edge (in cm)?
  17. 17.A cube has a volume of 27 cubic cm. How long is each edge (in cm)?
  18. 18.What is ∛8? =
  19. 19.Which of these is a perfect cube? (a) 2442 (b) 2197 (c) 2263
  20. 20.What is 2³? =
  21. 21.Which of these is a perfect cube? (a) 343 (b) 477 (c) 403
  22. 22.Which of these is a perfect cube? (a) 3800 (b) 3931 (c) 3375
  23. 23.What is 14³? =
  24. 24.What is ∛343? =
  25. 25.A big cube of edge 24 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  26. 26.A big cube of edge 15 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  27. 27.What is the smallest whole number by which 192 must be divided to get a perfect cube?
  28. 28.What is the smallest whole number by which 243 must be multiplied to get a perfect cube?
  29. 29.A big cube of edge 8 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  30. 30.A big cube of edge 5 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  31. 31.A cube has a volume of 2744 cubic cm. How long is each edge (in cm)?
  32. 32.What is ∛729? =
  33. 33.What is the smallest whole number by which 16 must be divided to get a perfect cube?
  34. 34.What is the smallest whole number by which 500 must be multiplied to get a perfect cube?
  35. 35.What is ∛8000? =
  36. 36.What is 15³? =
  37. 37.Which of these is a perfect cube? (a) 92 (b) 64 (c) 100
  38. 38.What is the smallest whole number by which 81 must be divided to get a perfect cube?
  39. 39.What is ∛512? =
  40. 40.What is ∛4913? =

Answer key

  1. 18
  2. 49
  3. 7
  4. 1728
  5. 4
  6. 1000
  7. 4913
  8. 25
  9. 27
  10. 27
  11. 2
  12. 2744
  13. 2
  14. 27
  15. 9
  16. 2
  17. 3
  18. 2
  19. 2197
  20. 8
  21. 343
  22. 3375
  23. 2744
  24. 7
  25. 216
  26. 125
  27. 3
  28. 3
  29. 8
  30. 125
  31. 14
  32. 9
  33. 2
  34. 2
  35. 20
  36. 3375
  37. 64
  38. 3
  39. 8
  40. 17

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