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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 678 · 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 the smallest whole number by which 1080 must be divided to get a perfect cube?
  2. 2.A big cube of edge 3 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  3. 3.A cube has a volume of 1000 cubic cm. How long is each edge (in cm)?
  4. 4.A big cube of edge 10 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  5. 5.A big cube of edge 4 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  6. 6.What is ∛13824? =
  7. 7.What is the smallest whole number by which 3 must be multiplied to get a perfect cube?
  8. 8.Which of these is a perfect cube? (a) 3151 (b) 2788 (c) 2744
  9. 9.A cube has a volume of 6859 cubic cm. How long is each edge (in cm)?
  10. 10.What is the smallest whole number by which 5 must be divided to get a perfect cube?
  11. 11.What is the smallest whole number by which 200 must be divided to get a perfect cube?
  12. 12.Which of these is a perfect cube? (a) 90 (b) 64 (c) 84
  13. 13.What is the smallest whole number by which 25 must be divided to get a perfect cube?
  14. 14.A big cube of edge 5 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  15. 15.What is the smallest whole number by which 5 must be multiplied to get a perfect cube?
  16. 16.A big cube of edge 8 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  17. 17.What is 8³? =
  18. 18.What is ∛1331? =
  19. 19.What is 18³? =
  20. 20.What is the smallest whole number by which 375 must be divided to get a perfect cube?
  21. 21.What is 9³? =
  22. 22.Which of these is a perfect cube? (a) 2197 (b) 2324 (c) 2550
  23. 23.Which of these is a perfect cube? (a) 3406 (b) 3853 (c) 3375
  24. 24.A big cube of edge 16 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  25. 25.What is the smallest whole number by which 49 must be multiplied to get a perfect cube?
  26. 26.A cube has a volume of 125 cubic cm. How long is each edge (in cm)?
  27. 27.What is the smallest whole number by which 1944 must be divided to get a perfect cube?
  28. 28.What is ∛1000? =
  29. 29.A big cube of edge 6 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  30. 30.Which of these is a perfect cube? (a) 178 (b) 155 (c) 125
  31. 31.Which of these is a perfect cube? (a) 1036 (b) 1042 (c) 1000
  32. 32.What is the smallest whole number by which 135 must be multiplied to get a perfect cube?
  33. 33.Which of these is a perfect cube? (a) 293 (b) 275 (c) 216
  34. 34.What is 7³? =
  35. 35.A big cube of edge 8 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  36. 36.What is ∛5832? =
  37. 37.What is ∛15625? =
  38. 38.What is 17³? =
  39. 39.What is ∛3375? =
  40. 40.What is the smallest whole number by which 625 must be divided to get a perfect cube?

Answer key

  1. 5
  2. 27
  3. 10
  4. 125
  5. 64
  6. 24
  7. 9
  8. 2744
  9. 19
  10. 5
  11. 25
  12. 64
  13. 25
  14. 125
  15. 25
  16. 8
  17. 512
  18. 11
  19. 5832
  20. 3
  21. 729
  22. 2197
  23. 3375
  24. 64
  25. 7
  26. 5
  27. 9
  28. 10
  29. 8
  30. 125
  31. 1000
  32. 25
  33. 216
  34. 343
  35. 64
  36. 18
  37. 25
  38. 4913
  39. 15
  40. 5

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