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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 273 · 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 3³? =
  3. 3.What is ∛8000? =
  4. 4.A big cube of edge 24 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  5. 5.Which of these is a perfect cube? (a) 3735 (b) 3777 (c) 3375
  6. 6.A big cube of edge 6 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  7. 7.A big cube of edge 5 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  8. 8.A cube has a volume of 64 cubic cm. How long is each edge (in cm)?
  9. 9.Which of these is a perfect cube? (a) 216 (b) 302 (c) 295
  10. 10.What is 19³? =
  11. 11.What is the smallest whole number by which 40 must be multiplied to get a perfect cube?
  12. 12.A big cube of edge 9 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  13. 13.What is 15³? =
  14. 14.What is 20³? =
  15. 15.A big cube of edge 12 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  16. 16.What is 6³? =
  17. 17.What is the smallest whole number by which 250 must be divided to get a perfect cube?
  18. 18.What is 9³? =
  19. 19.Which of these is a perfect cube? (a) 1728 (b) 1985 (c) 2147
  20. 20.A cube has a volume of 1331 cubic cm. How long is each edge (in cm)?
  21. 21.What is the smallest whole number by which 9 must be divided to get a perfect cube?
  22. 22.What is ∛1728? =
  23. 23.What is the smallest whole number by which 1600 must be divided to get a perfect cube?
  24. 24.Which of these is a perfect cube? (a) 2744 (b) 3246 (c) 3292
  25. 25.What is the smallest whole number by which 189 must be divided to get a perfect cube?
  26. 26.What is ∛2197? =
  27. 27.What is ∛216? =
  28. 28.What is the smallest whole number by which 648 must be multiplied to get a perfect cube?
  29. 29.A cube has a volume of 4096 cubic cm. How long is each edge (in cm)?
  30. 30.Which of these is a perfect cube? (a) 64 (b) 88 (c) 103
  31. 31.A big cube of edge 4 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  32. 32.A big cube of edge 2 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  33. 33.What is ∛729? =
  34. 34.A big cube of edge 6 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  35. 35.A cube has a volume of 343 cubic cm. How long is each edge (in cm)?
  36. 36.What is 17³? =
  37. 37.What is 12³? =
  38. 38.What is ∛9261? =
  39. 39.What is 2³? =
  40. 40.What is the smallest whole number by which 200 must be divided to get a perfect cube?

Answer key

  1. 5832
  2. 27
  3. 20
  4. 216
  5. 3375
  6. 8
  7. 125
  8. 4
  9. 216
  10. 6859
  11. 25
  12. 27
  13. 3375
  14. 8000
  15. 27
  16. 216
  17. 2
  18. 729
  19. 1728
  20. 11
  21. 9
  22. 12
  23. 25
  24. 2744
  25. 7
  26. 13
  27. 6
  28. 9
  29. 16
  30. 64
  31. 64
  32. 8
  33. 9
  34. 27
  35. 7
  36. 4913
  37. 1728
  38. 21
  39. 8
  40. 25

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