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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 389 · 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 the smallest whole number by which 648 must be multiplied to get a perfect cube?
  2. 2.What is ∛4913? =
  3. 3.What is the smallest whole number by which 5400 must be divided to get a perfect cube?
  4. 4.What is 8³? =
  5. 5.A cube has a volume of 8 cubic cm. How long is each edge (in cm)?
  6. 6.A cube has a volume of 1331 cubic cm. How long is each edge (in cm)?
  7. 7.A big cube of edge 4 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  8. 8.A cube has a volume of 216 cubic cm. How long is each edge (in cm)?
  9. 9.What is the smallest whole number by which 1944 must be multiplied to get a perfect cube?
  10. 10.A big cube of edge 15 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  11. 11.What is the smallest whole number by which 675 must be divided to get a perfect cube?
  12. 12.Which of these is a perfect cube? (a) 343 (b) 351 (c) 365
  13. 13.What is 20³? =
  14. 14.What is 12³? =
  15. 15.A big cube of edge 6 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  16. 16.A cube has a volume of 125 cubic cm. How long is each edge (in cm)?
  17. 17.What is ∛5832? =
  18. 18.What is the smallest whole number by which 1323 must be multiplied to get a perfect cube?
  19. 19.What is the smallest whole number by which 72 must be multiplied to get a perfect cube?
  20. 20.A big cube of edge 16 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  21. 21.What is ∛64? =
  22. 22.What is ∛15625? =
  23. 23.A big cube of edge 6 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  24. 24.What is ∛1000? =
  25. 25.Which of these is a perfect cube? (a) 665 (b) 512 (c) 556
  26. 26.A big cube of edge 20 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  27. 27.A cube has a volume of 2197 cubic cm. How long is each edge (in cm)?
  28. 28.What is 19³? =
  29. 29.What is 18³? =
  30. 30.Which of these is a perfect cube? (a) 98 (b) 78 (c) 64
  31. 31.A big cube of edge 3 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  32. 32.Which of these is a perfect cube? (a) 3017 (b) 2744 (c) 2828
  33. 33.What is ∛1331? =
  34. 34.A cube has a volume of 27 cubic cm. How long is each edge (in cm)?
  35. 35.What is ∛343? =
  36. 36.What is 13³? =
  37. 37.What is 16³? =
  38. 38.What is 14³? =
  39. 39.A cube has a volume of 343 cubic cm. How long is each edge (in cm)?
  40. 40.A big cube of edge 24 cm is cut into small cubes of edge 4 cm. How many small cubes are there?

Answer key

  1. 9
  2. 17
  3. 25
  4. 512
  5. 2
  6. 11
  7. 64
  8. 6
  9. 3
  10. 125
  11. 25
  12. 343
  13. 8000
  14. 1728
  15. 216
  16. 5
  17. 18
  18. 7
  19. 3
  20. 64
  21. 4
  22. 25
  23. 27
  24. 10
  25. 512
  26. 125
  27. 13
  28. 6859
  29. 5832
  30. 64
  31. 27
  32. 2744
  33. 11
  34. 3
  35. 7
  36. 2197
  37. 4096
  38. 2744
  39. 7
  40. 216

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