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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 397 · 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 10 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  2. 2.What is the smallest whole number by which 56 must be multiplied to get a perfect cube?
  3. 3.What is the smallest whole number by which 54 must be divided to get a perfect cube?
  4. 4.What is ∛15625? =
  5. 5.What is ∛1728? =
  6. 6.A big cube of edge 12 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  7. 7.What is ∛343? =
  8. 8.A big cube of edge 15 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  9. 9.What is ∛729? =
  10. 10.What is ∛1331? =
  11. 11.Which of these is a perfect cube? (a) 1983 (b) 1728 (c) 2071
  12. 12.What is the smallest whole number by which 432 must be divided to get a perfect cube?
  13. 13.A cube has a volume of 1331 cubic cm. How long is each edge (in cm)?
  14. 14.What is the smallest whole number by which 320 must be multiplied to get a perfect cube?
  15. 15.What is 19³? =
  16. 16.A cube has a volume of 5832 cubic cm. How long is each edge (in cm)?
  17. 17.What is 6³? =
  18. 18.A big cube of edge 6 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  19. 19.A cube has a volume of 1000 cubic cm. How long is each edge (in cm)?
  20. 20.What is the smallest whole number by which 375 must be multiplied to get a perfect cube?
  21. 21.What is 4³? =
  22. 22.What is 10³? =
  23. 23.What is 11³? =
  24. 24.A cube has a volume of 729 cubic cm. How long is each edge (in cm)?
  25. 25.What is ∛6859? =
  26. 26.A cube has a volume of 8 cubic cm. How long is each edge (in cm)?
  27. 27.What is the smallest whole number by which 625 must be divided to get a perfect cube?
  28. 28.What is the smallest whole number by which 250 must be divided to get a perfect cube?
  29. 29.A big cube of edge 16 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  30. 30.A cube has a volume of 216 cubic cm. How long is each edge (in cm)?
  31. 31.What is the smallest whole number by which 32 must be divided to get a perfect cube?
  32. 32.A cube has a volume of 125 cubic cm. How long is each edge (in cm)?
  33. 33.What is ∛125? =
  34. 34.What is the smallest whole number by which 4 must be divided to get a perfect cube?
  35. 35.What is ∛216? =
  36. 36.A big cube of edge 6 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  37. 37.What is 12³? =
  38. 38.What is ∛13824? =
  39. 39.What is 15³? =
  40. 40.A big cube of edge 4 cm is cut into small cubes of edge 2 cm. How many small cubes are there?

Answer key

  1. 125
  2. 49
  3. 2
  4. 25
  5. 12
  6. 64
  7. 7
  8. 125
  9. 9
  10. 11
  11. 1728
  12. 2
  13. 11
  14. 25
  15. 6859
  16. 18
  17. 216
  18. 27
  19. 10
  20. 9
  21. 64
  22. 1000
  23. 1331
  24. 9
  25. 19
  26. 2
  27. 5
  28. 2
  29. 64
  30. 6
  31. 4
  32. 5
  33. 5
  34. 4
  35. 6
  36. 216
  37. 1728
  38. 24
  39. 3375
  40. 8

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