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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 649 · 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.Which of these is a perfect cube? (a) 39 (b) 27 (c) 50
  2. 2.A big cube of edge 8 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  3. 3.A big cube of edge 20 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  4. 4.A big cube of edge 6 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  5. 5.What is ∛125? =
  6. 6.A cube has a volume of 1728 cubic cm. How long is each edge (in cm)?
  7. 7.A cube has a volume of 2744 cubic cm. How long is each edge (in cm)?
  8. 8.What is the smallest whole number by which 6125 must be multiplied to get a perfect cube?
  9. 9.What is ∛64? =
  10. 10.What is the smallest whole number by which 6125 must be divided to get a perfect cube?
  11. 11.Which of these is a perfect cube? (a) 2676 (b) 2350 (c) 2197
  12. 12.Which of these is a perfect cube? (a) 1728 (b) 2127 (c) 1851
  13. 13.What is the smallest whole number by which 1125 must be divided to get a perfect cube?
  14. 14.A big cube of edge 15 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  15. 15.What is the smallest whole number by which 10584 must be multiplied to get a perfect cube?
  16. 16.A cube has a volume of 343 cubic cm. How long is each edge (in cm)?
  17. 17.What is 16³? =
  18. 18.A big cube of edge 9 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  19. 19.A cube has a volume of 4096 cubic cm. How long is each edge (in cm)?
  20. 20.What is the smallest whole number by which 4 must be divided to get a perfect cube?
  21. 21.A big cube of edge 6 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  22. 22.What is 11³? =
  23. 23.Which of these is a perfect cube? (a) 1037 (b) 1000 (c) 1138
  24. 24.A cube has a volume of 27 cubic cm. How long is each edge (in cm)?
  25. 25.What is ∛2197? =
  26. 26.What is 15³? =
  27. 27.What is ∛1331? =
  28. 28.Which of these is a perfect cube? (a) 512 (b) 539 (c) 697
  29. 29.A big cube of edge 4 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  30. 30.A big cube of edge 5 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  31. 31.What is the smallest whole number by which 192 must be divided to get a perfect cube?
  32. 32.What is ∛512? =
  33. 33.What is ∛9261? =
  34. 34.What is ∛13824? =
  35. 35.A cube has a volume of 8000 cubic cm. How long is each edge (in cm)?
  36. 36.What is the smallest whole number by which 1323 must be multiplied to get a perfect cube?
  37. 37.What is 4³? =
  38. 38.What is 7³? =
  39. 39.What is 3³? =
  40. 40.What is the smallest whole number by which 375 must be multiplied to get a perfect cube?

Answer key

  1. 27
  2. 8
  3. 125
  4. 8
  5. 5
  6. 12
  7. 14
  8. 7
  9. 4
  10. 49
  11. 2197
  12. 1728
  13. 9
  14. 125
  15. 7
  16. 7
  17. 4096
  18. 27
  19. 16
  20. 4
  21. 27
  22. 1331
  23. 1000
  24. 3
  25. 13
  26. 3375
  27. 11
  28. 512
  29. 64
  30. 125
  31. 3
  32. 8
  33. 21
  34. 24
  35. 20
  36. 7
  37. 64
  38. 343
  39. 27
  40. 9

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