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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 547 · 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.A big cube of edge 16 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  2. 2.Which of these is a perfect cube? (a) 249 (b) 216 (c) 224
  3. 3.What is ∛64? =
  4. 4.What is ∛8? =
  5. 5.What is ∛5832? =
  6. 6.What is 19³? =
  7. 7.What is ∛10648? =
  8. 8.What is ∛4096? =
  9. 9.What is 8³? =
  10. 10.What is ∛3375? =
  11. 11.A big cube of edge 2 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  12. 12.What is 15³? =
  13. 13.What is 10³? =
  14. 14.Which of these is a perfect cube? (a) 762 (b) 845 (c) 729
  15. 15.What is ∛343? =
  16. 16.What is the smallest whole number by which 200 must be multiplied to get a perfect cube?
  17. 17.What is ∛1728? =
  18. 18.What is the smallest whole number by which 6125 must be multiplied to get a perfect cube?
  19. 19.What is the smallest whole number by which 32 must be divided to get a perfect cube?
  20. 20.A cube has a volume of 1331 cubic cm. How long is each edge (in cm)?
  21. 21.A cube has a volume of 5832 cubic cm. How long is each edge (in cm)?
  22. 22.A cube has a volume of 1000 cubic cm. How long is each edge (in cm)?
  23. 23.A big cube of edge 6 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  24. 24.A cube has a volume of 125 cubic cm. How long is each edge (in cm)?
  25. 25.Which of these is a perfect cube? (a) 46 (b) 27 (c) 51
  26. 26.A big cube of edge 24 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  27. 27.What is the smallest whole number by which 189 must be multiplied to get a perfect cube?
  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 675 must be divided to get a perfect cube?
  30. 30.Which of these is a perfect cube? (a) 86 (b) 72 (c) 64
  31. 31.Which of these is a perfect cube? (a) 467 (b) 343 (c) 446
  32. 32.Which of these is a perfect cube? (a) 1620 (b) 1340 (c) 1331
  33. 33.A big cube of edge 8 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  34. 34.What is the smallest whole number by which 108 must be multiplied to get a perfect cube?
  35. 35.What is the smallest whole number by which 576 must be divided to get a perfect cube?
  36. 36.What is 5³? =
  37. 37.What is 11³? =
  38. 38.Which of these is a perfect cube? (a) 189 (b) 125 (c) 151
  39. 39.Which of these is a perfect cube? (a) 2340 (b) 2197 (c) 2223
  40. 40.What is ∛125? =

Answer key

  1. 64
  2. 216
  3. 4
  4. 2
  5. 18
  6. 6859
  7. 22
  8. 16
  9. 512
  10. 15
  11. 8
  12. 3375
  13. 1000
  14. 729
  15. 7
  16. 5
  17. 12
  18. 7
  19. 4
  20. 11
  21. 18
  22. 10
  23. 216
  24. 5
  25. 27
  26. 216
  27. 49
  28. 125
  29. 25
  30. 64
  31. 343
  32. 1331
  33. 64
  34. 2
  35. 9
  36. 125
  37. 1331
  38. 125
  39. 2197
  40. 5

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