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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 23 · 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 19³? =
  3. 3.Which of these is a perfect cube? (a) 110 (b) 64 (c) 66
  4. 4.What is 15³? =
  5. 5.A big cube of edge 12 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  6. 6.Which of these is a perfect cube? (a) 2976 (b) 2860 (c) 2744
  7. 7.What is 7³? =
  8. 8.What is ∛4913? =
  9. 9.What is the smallest whole number by which 192 must be multiplied to get a perfect cube?
  10. 10.A big cube of edge 9 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  11. 11.What is 12³? =
  12. 12.Which of these is a perfect cube? (a) 1152 (b) 1059 (c) 1000
  13. 13.What is ∛8? =
  14. 14.What is 14³? =
  15. 15.A big cube of edge 20 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  16. 16.Which of these is a perfect cube? (a) 294 (b) 216 (c) 258
  17. 17.Which of these is a perfect cube? (a) 53 (b) 27 (c) 41
  18. 18.A cube has a volume of 216 cubic cm. How long is each edge (in cm)?
  19. 19.Which of these is a perfect cube? (a) 3882 (b) 3968 (c) 3375
  20. 20.A cube has a volume of 125 cubic cm. How long is each edge (in cm)?
  21. 21.What is 6³? =
  22. 22.What is ∛1000? =
  23. 23.What is ∛125? =
  24. 24.What is the smallest whole number by which 108 must be multiplied to get a perfect cube?
  25. 25.What is ∛15625? =
  26. 26.A cube has a volume of 729 cubic cm. How long is each edge (in cm)?
  27. 27.What is ∛512? =
  28. 28.What is ∛3375? =
  29. 29.What is the smallest whole number by which 81 must be multiplied to get a perfect cube?
  30. 30.What is the smallest whole number by which 9 must be divided to get a perfect cube?
  31. 31.What is the smallest whole number by which 9 must be multiplied to get a perfect cube?
  32. 32.What is 2³? =
  33. 33.A cube has a volume of 27 cubic cm. How long is each edge (in cm)?
  34. 34.A big cube of edge 8 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  35. 35.What is 5³? =
  36. 36.Which of these is a perfect cube? (a) 1728 (b) 1839 (c) 2138
  37. 37.A big cube of edge 5 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  38. 38.Which of these is a perfect cube? (a) 137 (b) 125 (c) 186
  39. 39.What is 18³? =
  40. 40.What is the smallest whole number by which 200 must be divided to get a perfect cube?

Answer key

  1. 20
  2. 6859
  3. 64
  4. 3375
  5. 216
  6. 2744
  7. 343
  8. 17
  9. 9
  10. 27
  11. 1728
  12. 1000
  13. 2
  14. 2744
  15. 125
  16. 216
  17. 27
  18. 6
  19. 3375
  20. 5
  21. 216
  22. 10
  23. 5
  24. 2
  25. 25
  26. 9
  27. 8
  28. 15
  29. 9
  30. 9
  31. 3
  32. 8
  33. 3
  34. 8
  35. 125
  36. 1728
  37. 125
  38. 125
  39. 5832
  40. 25

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