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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 351 · 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 3 must be divided to get a perfect cube?
  2. 2.What is ∛64? =
  3. 3.What is the smallest whole number by which 9 must be divided to get a perfect cube?
  4. 4.What is 2³? =
  5. 5.A big cube of edge 8 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  6. 6.Which of these is a perfect cube? (a) 3607 (b) 3375 (c) 4049
  7. 7.What is ∛216? =
  8. 8.A big cube of edge 5 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  9. 9.A big cube of edge 9 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  10. 10.A big cube of edge 4 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  11. 11.A cube has a volume of 216 cubic cm. How long is each edge (in cm)?
  12. 12.A cube has a volume of 64 cubic cm. How long is each edge (in cm)?
  13. 13.What is ∛1728? =
  14. 14.What is 14³? =
  15. 15.Which of these is a perfect cube? (a) 1343 (b) 1331 (c) 1444
  16. 16.Which of these is a perfect cube? (a) 54 (b) 27 (c) 31
  17. 17.What is 8³? =
  18. 18.What is ∛125? =
  19. 19.Which of these is a perfect cube? (a) 166 (b) 125 (c) 134
  20. 20.A cube has a volume of 4913 cubic cm. How long is each edge (in cm)?
  21. 21.What is ∛2744? =
  22. 22.What is ∛512? =
  23. 23.What is the smallest whole number by which 1600 must be divided to get a perfect cube?
  24. 24.Which of these is a perfect cube? (a) 427 (b) 343 (c) 461
  25. 25.What is the smallest whole number by which 1125 must be divided to get a perfect cube?
  26. 26.What is ∛343? =
  27. 27.What is the smallest whole number by which 1512 must be multiplied to get a perfect cube?
  28. 28.What is 6³? =
  29. 29.Which of these is a perfect cube? (a) 2910 (b) 3020 (c) 2744
  30. 30.What is the smallest whole number by which 392 must be multiplied to get a perfect cube?
  31. 31.What is ∛10648? =
  32. 32.What is the smallest whole number by which 49 must be multiplied to get a perfect cube?
  33. 33.A cube has a volume of 2197 cubic cm. How long is each edge (in cm)?
  34. 34.What is 9³? =
  35. 35.What is the smallest whole number by which 1600 must be multiplied to get a perfect cube?
  36. 36.A cube has a volume of 8 cubic cm. How long is each edge (in cm)?
  37. 37.A cube has a volume of 1728 cubic cm. How long is each edge (in cm)?
  38. 38.What is 20³? =
  39. 39.A big cube of edge 24 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  40. 40.A cube has a volume of 4096 cubic cm. How long is each edge (in cm)?

Answer key

  1. 3
  2. 4
  3. 9
  4. 8
  5. 8
  6. 3375
  7. 6
  8. 125
  9. 27
  10. 8
  11. 6
  12. 4
  13. 12
  14. 2744
  15. 1331
  16. 27
  17. 512
  18. 5
  19. 125
  20. 17
  21. 14
  22. 8
  23. 25
  24. 343
  25. 9
  26. 7
  27. 49
  28. 216
  29. 2744
  30. 7
  31. 22
  32. 7
  33. 13
  34. 729
  35. 5
  36. 2
  37. 12
  38. 8000
  39. 216
  40. 16

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