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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 339 · 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 1125 must be divided to get a perfect cube?
  2. 2.What is the smallest whole number by which 3 must be multiplied to get a perfect cube?
  3. 3.Which of these is a perfect cube? (a) 384 (b) 343 (c) 355
  4. 4.Which of these is a perfect cube? (a) 2278 (b) 2197 (c) 2584
  5. 5.What is 12³? =
  6. 6.What is ∛6859? =
  7. 7.What is 4³? =
  8. 8.What is ∛13824? =
  9. 9.A cube has a volume of 64 cubic cm. How long is each edge (in cm)?
  10. 10.Which of these is a perfect cube? (a) 1806 (b) 1728 (c) 1884
  11. 11.What is 20³? =
  12. 12.A cube has a volume of 4096 cubic cm. How long is each edge (in cm)?
  13. 13.A cube has a volume of 343 cubic cm. How long is each edge (in cm)?
  14. 14.A big cube of edge 6 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  15. 15.A big cube of edge 18 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  16. 16.Which of these is a perfect cube? (a) 3031 (b) 2747 (c) 2744
  17. 17.What is the smallest whole number by which 320 must be multiplied to get a perfect cube?
  18. 18.What is 14³? =
  19. 19.A cube has a volume of 5832 cubic cm. How long is each edge (in cm)?
  20. 20.What is the smallest whole number by which 875 must be divided to get a perfect cube?
  21. 21.What is ∛216? =
  22. 22.What is the smallest whole number by which 243 must be divided to get a perfect cube?
  23. 23.A cube has a volume of 8 cubic cm. How long is each edge (in cm)?
  24. 24.Which of these is a perfect cube? (a) 42 (b) 27 (c) 31
  25. 25.What is ∛15625? =
  26. 26.Which of these is a perfect cube? (a) 1148 (b) 1000 (c) 1119
  27. 27.What is 10³? =
  28. 28.What is 18³? =
  29. 29.What is the smallest whole number by which 189 must be multiplied to get a perfect cube?
  30. 30.What is the smallest whole number by which 648 must be divided to get a perfect cube?
  31. 31.What is the smallest whole number by which 56 must be multiplied to get a perfect cube?
  32. 32.Which of these is a perfect cube? (a) 135 (b) 195 (c) 125
  33. 33.A cube has a volume of 512 cubic cm. How long is each edge (in cm)?
  34. 34.A big cube of edge 4 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  35. 35.What is 9³? =
  36. 36.What is the smallest whole number by which 243 must be multiplied to get a perfect cube?
  37. 37.Which of these is a perfect cube? (a) 729 (b) 842 (c) 875
  38. 38.What is 2³? =
  39. 39.A big cube of edge 4 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  40. 40.What is 7³? =

Answer key

  1. 9
  2. 9
  3. 343
  4. 2197
  5. 1728
  6. 19
  7. 64
  8. 24
  9. 4
  10. 1728
  11. 8000
  12. 16
  13. 7
  14. 27
  15. 216
  16. 2744
  17. 25
  18. 2744
  19. 18
  20. 7
  21. 6
  22. 9
  23. 2
  24. 27
  25. 25
  26. 1000
  27. 1000
  28. 5832
  29. 49
  30. 3
  31. 49
  32. 125
  33. 8
  34. 64
  35. 729
  36. 3
  37. 729
  38. 8
  39. 8
  40. 343

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