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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 946 · 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) 3546 (b) 3375 (c) 4044
  2. 2.What is 19³? =
  3. 3.Which of these is a perfect cube? (a) 125 (b) 151 (c) 178
  4. 4.What is the smallest whole number by which 392 must be multiplied to get a perfect cube?
  5. 5.What is the smallest whole number by which 40 must be divided to get a perfect cube?
  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.What is the smallest whole number by which 40 must be multiplied to get a perfect cube?
  8. 8.Which of these is a perfect cube? (a) 314 (b) 216 (c) 240
  9. 9.A big cube of edge 24 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  10. 10.What is the smallest whole number by which 375 must be multiplied to get a perfect cube?
  11. 11.A cube has a volume of 1000 cubic cm. How long is each edge (in cm)?
  12. 12.What is the smallest whole number by which 54 must be divided to get a perfect cube?
  13. 13.A cube has a volume of 125 cubic cm. How long is each edge (in cm)?
  14. 14.What is ∛8000? =
  15. 15.What is 14³? =
  16. 16.A big cube of edge 4 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  17. 17.What is the smallest whole number by which 2 must be divided to get a perfect cube?
  18. 18.What is 4³? =
  19. 19.What is the smallest whole number by which 4 must be multiplied to get a perfect cube?
  20. 20.What is ∛343? =
  21. 21.What is ∛125? =
  22. 22.A cube has a volume of 3375 cubic cm. How long is each edge (in cm)?
  23. 23.A cube has a volume of 8 cubic cm. How long is each edge (in cm)?
  24. 24.What is 18³? =
  25. 25.What is 15³? =
  26. 26.What is 16³? =
  27. 27.What is the smallest whole number by which 4 must be divided to get a perfect cube?
  28. 28.A cube has a volume of 1728 cubic cm. How long is each edge (in cm)?
  29. 29.What is ∛27? =
  30. 30.What is 11³? =
  31. 31.What is ∛1331? =
  32. 32.What is the smallest whole number by which 375 must be divided to get a perfect cube?
  33. 33.What is ∛1000? =
  34. 34.Which of these is a perfect cube? (a) 1745 (b) 1728 (c) 1889
  35. 35.A cube has a volume of 6859 cubic cm. How long is each edge (in cm)?
  36. 36.What is 6³? =
  37. 37.Which of these is a perfect cube? (a) 3206 (b) 3139 (c) 2744
  38. 38.What is ∛64? =
  39. 39.What is the smallest whole number by which 243 must be multiplied to get a perfect cube?
  40. 40.What is 13³? =

Answer key

  1. 3375
  2. 6859
  3. 125
  4. 7
  5. 5
  6. 8
  7. 25
  8. 216
  9. 216
  10. 9
  11. 10
  12. 2
  13. 5
  14. 20
  15. 2744
  16. 64
  17. 2
  18. 64
  19. 2
  20. 7
  21. 5
  22. 15
  23. 2
  24. 5832
  25. 3375
  26. 4096
  27. 4
  28. 12
  29. 3
  30. 1331
  31. 11
  32. 3
  33. 10
  34. 1728
  35. 19
  36. 216
  37. 2744
  38. 4
  39. 3
  40. 2197

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