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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 691 · 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 15³? =
  2. 2.What is 3³? =
  3. 3.Which of these is a perfect cube? (a) 216 (b) 243 (c) 237
  4. 4.What is the smallest whole number by which 81 must be multiplied to get a perfect cube?
  5. 5.Which of these is a perfect cube? (a) 729 (b) 803 (c) 754
  6. 6.Which of these is a perfect cube? (a) 381 (b) 343 (c) 454
  7. 7.What is 14³? =
  8. 8.A big cube of edge 12 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  9. 9.A cube has a volume of 2197 cubic cm. How long is each edge (in cm)?
  10. 10.What is 9³? =
  11. 11.What is 12³? =
  12. 12.What is the smallest whole number by which 49 must be multiplied to get a perfect cube?
  13. 13.What is 5³? =
  14. 14.Which of these is a perfect cube? (a) 1000 (b) 1110 (c) 1135
  15. 15.Which of these is a perfect cube? (a) 2656 (b) 2491 (c) 2197
  16. 16.What is the smallest whole number by which 9 must be multiplied to get a perfect cube?
  17. 17.Which of these is a perfect cube? (a) 2744 (b) 3122 (c) 2792
  18. 18.A cube has a volume of 5832 cubic cm. How long is each edge (in cm)?
  19. 19.What is the smallest whole number by which 5400 must be multiplied to get a perfect cube?
  20. 20.What is 4³? =
  21. 21.Which of these is a perfect cube? (a) 125 (b) 135 (c) 149
  22. 22.A cube has a volume of 216 cubic cm. How long is each edge (in cm)?
  23. 23.What is ∛1331? =
  24. 24.What is 18³? =
  25. 25.What is 2³? =
  26. 26.What is ∛125? =
  27. 27.A cube has a volume of 8 cubic cm. How long is each edge (in cm)?
  28. 28.A big cube of edge 8 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  29. 29.What is 20³? =
  30. 30.What is the smallest whole number by which 675 must be multiplied to get a perfect cube?
  31. 31.What is ∛2197? =
  32. 32.A big cube of edge 12 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  33. 33.What is ∛4913? =
  34. 34.What is the smallest whole number by which 648 must be divided to get a perfect cube?
  35. 35.A cube has a volume of 4096 cubic cm. How long is each edge (in cm)?
  36. 36.A cube has a volume of 3375 cubic cm. How long is each edge (in cm)?
  37. 37.What is ∛64? =
  38. 38.What is 19³? =
  39. 39.What is ∛343? =
  40. 40.What is 10³? =

Answer key

  1. 3375
  2. 27
  3. 216
  4. 9
  5. 729
  6. 343
  7. 2744
  8. 27
  9. 13
  10. 729
  11. 1728
  12. 7
  13. 125
  14. 1000
  15. 2197
  16. 3
  17. 2744
  18. 18
  19. 5
  20. 64
  21. 125
  22. 6
  23. 11
  24. 5832
  25. 8
  26. 5
  27. 2
  28. 8
  29. 8000
  30. 5
  31. 13
  32. 216
  33. 17
  34. 3
  35. 16
  36. 15
  37. 4
  38. 6859
  39. 7
  40. 1000

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