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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 140 · 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 ∛8000? =
  2. 2.What is 17³? =
  3. 3.A cube has a volume of 2744 cubic cm. How long is each edge (in cm)?
  4. 4.Which of these is a perfect cube? (a) 1331 (b) 1392 (c) 1375
  5. 5.What is the smallest whole number by which 128 must be multiplied to get a perfect cube?
  6. 6.A cube has a volume of 2197 cubic cm. How long is each edge (in cm)?
  7. 7.A cube has a volume of 6859 cubic cm. How long is each edge (in cm)?
  8. 8.Which of these is a perfect cube? (a) 1000 (b) 1060 (c) 1281
  9. 9.A big cube of edge 12 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  10. 10.What is 19³? =
  11. 11.A big cube of edge 6 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  12. 12.Which of these is a perfect cube? (a) 64 (b) 84 (c) 92
  13. 13.What is the smallest whole number by which 4 must be multiplied to get a perfect cube?
  14. 14.What is 7³? =
  15. 15.What is 4³? =
  16. 16.What is the smallest whole number by which 200 must be multiplied to get a perfect cube?
  17. 17.What is the smallest whole number by which 3 must be multiplied to get a perfect cube?
  18. 18.What is the smallest whole number by which 16 must be divided to get a perfect cube?
  19. 19.A big cube of edge 6 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  20. 20.A cube has a volume of 125 cubic cm. How long is each edge (in cm)?
  21. 21.What is 13³? =
  22. 22.What is ∛1331? =
  23. 23.A cube has a volume of 64 cubic cm. How long is each edge (in cm)?
  24. 24.What is ∛729? =
  25. 25.What is the smallest whole number by which 135 must be multiplied to get a perfect cube?
  26. 26.What is the smallest whole number by which 54 must be divided to get a perfect cube?
  27. 27.What is ∛9261? =
  28. 28.What is the smallest whole number by which 3125 must be divided to get a perfect cube?
  29. 29.A big cube of edge 15 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  30. 30.What is the smallest whole number by which 256 must be divided to get a perfect cube?
  31. 31.What is the smallest whole number by which 648 must be divided to get a perfect cube?
  32. 32.What is the smallest whole number by which 576 must be divided to get a perfect cube?
  33. 33.What is the smallest whole number by which 448 must be multiplied to get a perfect cube?
  34. 34.What is 18³? =
  35. 35.What is the smallest whole number by which 320 must be divided to get a perfect cube?
  36. 36.What is 5³? =
  37. 37.A cube has a volume of 343 cubic cm. How long is each edge (in cm)?
  38. 38.A big cube of edge 8 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  39. 39.What is the smallest whole number by which 375 must be divided to get a perfect cube?
  40. 40.What is 8³? =

Answer key

  1. 20
  2. 4913
  3. 14
  4. 1331
  5. 4
  6. 13
  7. 19
  8. 1000
  9. 27
  10. 6859
  11. 27
  12. 64
  13. 2
  14. 343
  15. 64
  16. 5
  17. 9
  18. 2
  19. 216
  20. 5
  21. 2197
  22. 11
  23. 4
  24. 9
  25. 25
  26. 2
  27. 21
  28. 25
  29. 125
  30. 4
  31. 3
  32. 9
  33. 49
  34. 5832
  35. 5
  36. 125
  37. 7
  38. 64
  39. 3
  40. 512

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