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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 840 · 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 8³? =
  2. 2.A big cube of edge 20 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  3. 3.A big cube of edge 3 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  4. 4.What is the smallest whole number by which 432 must be divided to get a perfect cube?
  5. 5.Which of these is a perfect cube? (a) 1156 (b) 1021 (c) 1000
  6. 6.What is 12³? =
  7. 7.Which of these is a perfect cube? (a) 2744 (b) 3309 (c) 2789
  8. 8.What is ∛729? =
  9. 9.What is the smallest whole number by which 128 must be divided to get a perfect cube?
  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 ∛8000? =
  12. 12.A cube has a volume of 1331 cubic cm. How long is each edge (in cm)?
  13. 13.A cube has a volume of 4913 cubic cm. How long is each edge (in cm)?
  14. 14.Which of these is a perfect cube? (a) 35 (b) 46 (c) 27
  15. 15.Which of these is a perfect cube? (a) 3625 (b) 3375 (c) 3636
  16. 16.A cube has a volume of 1000 cubic cm. How long is each edge (in cm)?
  17. 17.A big cube of edge 2 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  18. 18.What is the smallest whole number by which 189 must be divided to get a perfect cube?
  19. 19.What is 17³? =
  20. 20.What is 9³? =
  21. 21.What is the smallest whole number by which 72 must be multiplied to get a perfect cube?
  22. 22.What is 7³? =
  23. 23.A cube has a volume of 4096 cubic cm. How long is each edge (in cm)?
  24. 24.What is the smallest whole number by which 392 must be divided to get a perfect cube?
  25. 25.Which of these is a perfect cube? (a) 226 (b) 216 (c) 243
  26. 26.A cube has a volume of 2744 cubic cm. How long is each edge (in cm)?
  27. 27.A big cube of edge 5 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  28. 28.What is 5³? =
  29. 29.What is ∛4913? =
  30. 30.Which of these is a perfect cube? (a) 125 (b) 134 (c) 160
  31. 31.What is 10³? =
  32. 32.A big cube of edge 4 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  33. 33.A big cube of edge 24 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  34. 34.What is the smallest whole number by which 3125 must be divided to get a perfect cube?
  35. 35.A big cube of edge 4 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  36. 36.What is ∛4096? =
  37. 37.A cube has a volume of 512 cubic cm. How long is each edge (in cm)?
  38. 38.What is the smallest whole number by which 500 must be divided to get a perfect cube?
  39. 39.What is the smallest whole number by which 576 must be divided to get a perfect cube?
  40. 40.What is the smallest whole number by which 108 must be divided to get a perfect cube?

Answer key

  1. 512
  2. 125
  3. 27
  4. 2
  5. 1000
  6. 1728
  7. 2744
  8. 9
  9. 2
  10. 27
  11. 20
  12. 11
  13. 17
  14. 27
  15. 3375
  16. 10
  17. 8
  18. 7
  19. 4913
  20. 729
  21. 3
  22. 343
  23. 16
  24. 49
  25. 216
  26. 14
  27. 125
  28. 125
  29. 17
  30. 125
  31. 1000
  32. 8
  33. 216
  34. 25
  35. 64
  36. 16
  37. 8
  38. 4
  39. 9
  40. 4

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