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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 375 · 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 20³? =
  2. 2.What is 3³? =
  3. 3.What is 4³? =
  4. 4.What is ∛3375? =
  5. 5.Which of these is a perfect cube? (a) 472 (b) 399 (c) 343
  6. 6.A cube has a volume of 343 cubic cm. How long is each edge (in cm)?
  7. 7.A big cube of edge 6 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  8. 8.A cube has a volume of 4913 cubic cm. How long is each edge (in cm)?
  9. 9.What is 19³? =
  10. 10.A cube has a volume of 2744 cubic cm. How long is each edge (in cm)?
  11. 11.What is ∛343? =
  12. 12.What is ∛4096? =
  13. 13.What is the smallest whole number by which 24 must be divided to get a perfect cube?
  14. 14.What is the smallest whole number by which 49 must be multiplied to get a perfect cube?
  15. 15.What is 5³? =
  16. 16.What is ∛125? =
  17. 17.What is the smallest whole number by which 250 must be multiplied to get a perfect cube?
  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 8000 cubic cm. How long is each edge (in cm)?
  20. 20.What is the smallest whole number by which 4 must be divided to get a perfect cube?
  21. 21.What is 6³? =
  22. 22.Which of these is a perfect cube? (a) 126 (b) 141 (c) 125
  23. 23.What is 11³? =
  24. 24.What is ∛4913? =
  25. 25.What is ∛64? =
  26. 26.A big cube of edge 12 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  27. 27.A cube has a volume of 27 cubic cm. How long is each edge (in cm)?
  28. 28.What is ∛15625? =
  29. 29.What is the smallest whole number by which 2 must be divided to get a perfect cube?
  30. 30.What is the smallest whole number by which 56 must be divided to get a perfect cube?
  31. 31.A big cube of edge 10 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  32. 32.Which of these is a perfect cube? (a) 110 (b) 105 (c) 64
  33. 33.What is 2³? =
  34. 34.What is the smallest whole number by which 3 must be divided to get a perfect cube?
  35. 35.What is 9³? =
  36. 36.What is 18³? =
  37. 37.Which of these is a perfect cube? (a) 1036 (b) 1000 (c) 1182
  38. 38.A cube has a volume of 125 cubic cm. How long is each edge (in cm)?
  39. 39.Which of these is a perfect cube? (a) 729 (b) 733 (c) 922
  40. 40.What is ∛5832? =

Answer key

  1. 8000
  2. 27
  3. 64
  4. 15
  5. 343
  6. 7
  7. 8
  8. 17
  9. 6859
  10. 14
  11. 7
  12. 16
  13. 3
  14. 7
  15. 125
  16. 5
  17. 4
  18. 27
  19. 20
  20. 4
  21. 216
  22. 125
  23. 1331
  24. 17
  25. 4
  26. 27
  27. 3
  28. 25
  29. 2
  30. 7
  31. 125
  32. 64
  33. 8
  34. 3
  35. 729
  36. 5832
  37. 1000
  38. 5
  39. 729
  40. 18

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