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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 939 · 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 6 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  2. 2.What is the smallest whole number by which 432 must be multiplied to get a perfect cube?
  3. 3.What is ∛8? =
  4. 4.Which of these is a perfect cube? (a) 1938 (b) 2104 (c) 1728
  5. 5.What is 13³? =
  6. 6.A cube has a volume of 2197 cubic cm. How long is each edge (in cm)?
  7. 7.What is the smallest whole number by which 128 must be multiplied to get a perfect cube?
  8. 8.What is the smallest whole number by which 648 must be divided to get a perfect cube?
  9. 9.A big cube of edge 8 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  10. 10.What is ∛343? =
  11. 11.What is ∛216? =
  12. 12.What is 7³? =
  13. 13.A big cube of edge 10 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  14. 14.A cube has a volume of 343 cubic cm. How long is each edge (in cm)?
  15. 15.A big cube of edge 4 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  16. 16.What is the smallest whole number by which 40 must be multiplied to get a perfect cube?
  17. 17.What is 9³? =
  18. 18.A big cube of edge 16 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  19. 19.Which of these is a perfect cube? (a) 352 (b) 343 (c) 459
  20. 20.Which of these is a perfect cube? (a) 304 (b) 216 (c) 245
  21. 21.Which of these is a perfect cube? (a) 75 (b) 80 (c) 64
  22. 22.What is 3³? =
  23. 23.Which of these is a perfect cube? (a) 146 (b) 125 (c) 136
  24. 24.Which of these is a perfect cube? (a) 3031 (b) 2744 (c) 2965
  25. 25.What is 6³? =
  26. 26.Which of these is a perfect cube? (a) 1274 (b) 1032 (c) 1000
  27. 27.A cube has a volume of 729 cubic cm. How long is each edge (in cm)?
  28. 28.A cube has a volume of 5832 cubic cm. How long is each edge (in cm)?
  29. 29.A cube has a volume of 125 cubic cm. How long is each edge (in cm)?
  30. 30.What is ∛1000? =
  31. 31.A big cube of edge 8 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  32. 32.What is ∛9261? =
  33. 33.A cube has a volume of 27 cubic cm. How long is each edge (in cm)?
  34. 34.What is 10³? =
  35. 35.A big cube of edge 3 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  36. 36.A big cube of edge 12 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  37. 37.A big cube of edge 4 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  38. 38.What is 20³? =
  39. 39.What is the smallest whole number by which 448 must be multiplied to get a perfect cube?
  40. 40.A big cube of edge 2 cm is cut into small cubes of edge 1 cm. How many small cubes are there?

Answer key

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

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