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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 965 · 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 multiplied to get a perfect cube?
  2. 2.What is ∛5832? =
  3. 3.What is 14³? =
  4. 4.Which of these is a perfect cube? (a) 910 (b) 926 (c) 729
  5. 5.Which of these is a perfect cube? (a) 2617 (b) 2197 (c) 2291
  6. 6.What is ∛27? =
  7. 7.What is ∛216? =
  8. 8.Which of these is a perfect cube? (a) 452 (b) 343 (c) 475
  9. 9.What is 20³? =
  10. 10.What is ∛4096? =
  11. 11.What is 4³? =
  12. 12.Which of these is a perfect cube? (a) 33 (b) 27 (c) 44
  13. 13.What is ∛8? =
  14. 14.Which of these is a perfect cube? (a) 595 (b) 643 (c) 512
  15. 15.A cube has a volume of 216 cubic cm. How long is each edge (in cm)?
  16. 16.A cube has a volume of 8000 cubic cm. How long is each edge (in cm)?
  17. 17.Which of these is a perfect cube? (a) 1331 (b) 1444 (c) 1436
  18. 18.A cube has a volume of 64 cubic cm. How long is each edge (in cm)?
  19. 19.What is ∛12167? =
  20. 20.Which of these is a perfect cube? (a) 259 (b) 295 (c) 216
  21. 21.What is the smallest whole number by which 243 must be divided to get a perfect cube?
  22. 22.A big cube of edge 12 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  23. 23.What is the smallest whole number by which 56 must be divided to get a perfect cube?
  24. 24.A big cube of edge 10 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  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.What is 17³? =
  27. 27.A big cube of edge 4 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  28. 28.A big cube of edge 5 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  29. 29.What is the smallest whole number by which 54 must be multiplied to get a perfect cube?
  30. 30.Which of these is a perfect cube? (a) 64 (b) 92 (c) 110
  31. 31.What is 9³? =
  32. 32.What is ∛13824? =
  33. 33.What is the smallest whole number by which 16 must be multiplied to get a perfect cube?
  34. 34.A cube has a volume of 2744 cubic cm. How long is each edge (in cm)?
  35. 35.What is ∛10648? =
  36. 36.A big cube of edge 6 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  37. 37.Which of these is a perfect cube? (a) 1000 (b) 1206 (c) 1080
  38. 38.A big cube of edge 8 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  39. 39.What is ∛64? =
  40. 40.What is the smallest whole number by which 25 must be divided to get a perfect cube?

Answer key

  1. 25
  2. 18
  3. 2744
  4. 729
  5. 2197
  6. 3
  7. 6
  8. 343
  9. 8000
  10. 16
  11. 64
  12. 27
  13. 2
  14. 512
  15. 6
  16. 20
  17. 1331
  18. 4
  19. 23
  20. 216
  21. 9
  22. 216
  23. 7
  24. 125
  25. 216
  26. 4913
  27. 8
  28. 125
  29. 4
  30. 64
  31. 729
  32. 24
  33. 4
  34. 14
  35. 22
  36. 8
  37. 1000
  38. 8
  39. 4
  40. 25

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