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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 881 · 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 18³? =
  2. 2.What is 17³? =
  3. 3.What is 12³? =
  4. 4.A cube has a volume of 125 cubic cm. How long is each edge (in cm)?
  5. 5.What is 10³? =
  6. 6.A big cube of edge 10 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  7. 7.A cube has a volume of 3375 cubic cm. How long is each edge (in cm)?
  8. 8.What is the smallest whole number by which 320 must be multiplied to get a perfect cube?
  9. 9.Which of these is a perfect cube? (a) 350 (b) 369 (c) 343
  10. 10.What is 4³? =
  11. 11.Which of these is a perfect cube? (a) 1350 (b) 1331 (c) 1494
  12. 12.What is ∛2197? =
  13. 13.Which of these is a perfect cube? (a) 2197 (b) 2461 (c) 2495
  14. 14.What is 2³? =
  15. 15.Which of these is a perfect cube? (a) 1984 (b) 2071 (c) 1728
  16. 16.A big cube of edge 20 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  17. 17.What is the smallest whole number by which 81 must be divided to get a perfect cube?
  18. 18.What is the smallest whole number by which 108 must be divided to get a perfect cube?
  19. 19.A big cube of edge 2 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  20. 20.What is 13³? =
  21. 21.What is the smallest whole number by which 9 must be divided to get a perfect cube?
  22. 22.A big cube of edge 8 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  23. 23.What is ∛4096? =
  24. 24.A big cube of edge 12 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  25. 25.What is 15³? =
  26. 26.A big cube of edge 6 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  27. 27.What is ∛64? =
  28. 28.What is the smallest whole number by which 128 must be divided to get a perfect cube?
  29. 29.What is ∛1331? =
  30. 30.What is ∛1728? =
  31. 31.What is ∛216? =
  32. 32.A cube has a volume of 8000 cubic cm. How long is each edge (in cm)?
  33. 33.Which of these is a perfect cube? (a) 3640 (b) 3474 (c) 3375
  34. 34.What is the smallest whole number by which 40 must be multiplied to get a perfect cube?
  35. 35.Which of these is a perfect cube? (a) 681 (b) 645 (c) 512
  36. 36.What is the smallest whole number by which 32 must be multiplied to get a perfect cube?
  37. 37.What is ∛125? =
  38. 38.What is 5³? =
  39. 39.What is the smallest whole number by which 49 must be multiplied to get a perfect cube?
  40. 40.What is 16³? =

Answer key

  1. 5832
  2. 4913
  3. 1728
  4. 5
  5. 1000
  6. 125
  7. 15
  8. 25
  9. 343
  10. 64
  11. 1331
  12. 13
  13. 2197
  14. 8
  15. 1728
  16. 125
  17. 3
  18. 4
  19. 8
  20. 2197
  21. 9
  22. 8
  23. 16
  24. 64
  25. 3375
  26. 27
  27. 4
  28. 2
  29. 11
  30. 12
  31. 6
  32. 20
  33. 3375
  34. 25
  35. 512
  36. 2
  37. 5
  38. 125
  39. 7
  40. 4096

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