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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 447 · 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 ∛1728? =
  2. 2.What is the smallest whole number by which 3136 must be divided to get a perfect cube?
  3. 3.What is 13³? =
  4. 4.What is the smallest whole number by which 5400 must be multiplied to get a perfect cube?
  5. 5.Which of these is a perfect cube? (a) 125 (b) 197 (c) 140
  6. 6.What is 8³? =
  7. 7.A cube has a volume of 729 cubic cm. How long is each edge (in cm)?
  8. 8.What is ∛2197? =
  9. 9.What is 3³? =
  10. 10.A big cube of edge 5 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  11. 11.What is 6³? =
  12. 12.A big cube of edge 8 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  13. 13.What is 15³? =
  14. 14.A cube has a volume of 2744 cubic cm. How long is each edge (in cm)?
  15. 15.What is ∛15625? =
  16. 16.A cube has a volume of 27 cubic cm. How long is each edge (in cm)?
  17. 17.What is the smallest whole number by which 3136 must be multiplied to get a perfect cube?
  18. 18.Which of these is a perfect cube? (a) 965 (b) 729 (c) 933
  19. 19.A cube has a volume of 8 cubic cm. How long is each edge (in cm)?
  20. 20.A cube has a volume of 1728 cubic cm. How long is each edge (in cm)?
  21. 21.Which of these is a perfect cube? (a) 236 (b) 216 (c) 266
  22. 22.Which of these is a perfect cube? (a) 108 (b) 64 (c) 103
  23. 23.What is the smallest whole number by which 250 must be divided to get a perfect cube?
  24. 24.Which of these is a perfect cube? (a) 1331 (b) 1629 (c) 1419
  25. 25.What is the smallest whole number by which 375 must be divided to get a perfect cube?
  26. 26.What is the smallest whole number by which 108 must be multiplied to get a perfect cube?
  27. 27.Which of these is a perfect cube? (a) 1830 (b) 2056 (c) 1728
  28. 28.What is ∛4096? =
  29. 29.What is the smallest whole number by which 4 must be divided to get a perfect cube?
  30. 30.A big cube of edge 6 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  31. 31.Which of these is a perfect cube? (a) 1063 (b) 1000 (c) 1031
  32. 32.What is the smallest whole number by which 3 must be divided to get a perfect cube?
  33. 33.A big cube of edge 20 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  34. 34.Which of these is a perfect cube? (a) 3856 (b) 3461 (c) 3375
  35. 35.What is the smallest whole number by which 9 must be multiplied to get a perfect cube?
  36. 36.A cube has a volume of 512 cubic cm. How long is each edge (in cm)?
  37. 37.What is 20³? =
  38. 38.What is the smallest whole number by which 189 must be divided to get a perfect cube?
  39. 39.A big cube of edge 12 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  40. 40.What is 9³? =

Answer key

  1. 12
  2. 49
  3. 2197
  4. 5
  5. 125
  6. 512
  7. 9
  8. 13
  9. 27
  10. 125
  11. 216
  12. 8
  13. 3375
  14. 14
  15. 25
  16. 3
  17. 7
  18. 729
  19. 2
  20. 12
  21. 216
  22. 64
  23. 2
  24. 1331
  25. 3
  26. 2
  27. 1728
  28. 16
  29. 4
  30. 27
  31. 1000
  32. 3
  33. 125
  34. 3375
  35. 3
  36. 8
  37. 8000
  38. 7
  39. 216
  40. 729

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