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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 497 · 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) 167 (b) 139 (c) 125
  2. 2.A cube has a volume of 1331 cubic cm. How long is each edge (in cm)?
  3. 3.What is the smallest whole number by which 1600 must be divided to get a perfect cube?
  4. 4.What is ∛15625? =
  5. 5.What is ∛1000? =
  6. 6.What is ∛4913? =
  7. 7.What is 16³? =
  8. 8.What is the smallest whole number by which 500 must be multiplied to get a perfect cube?
  9. 9.What is the smallest whole number by which 192 must be multiplied to get a perfect cube?
  10. 10.What is the smallest whole number by which 2 must be multiplied to get a perfect cube?
  11. 11.A cube has a volume of 125 cubic cm. How long is each edge (in cm)?
  12. 12.A big cube of edge 6 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  13. 13.What is ∛2197? =
  14. 14.A big cube of edge 4 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  15. 15.Which of these is a perfect cube? (a) 2197 (b) 2489 (c) 2393
  16. 16.What is the smallest whole number by which 135 must be divided to get a perfect cube?
  17. 17.What is ∛2744? =
  18. 18.Which of these is a perfect cube? (a) 68 (b) 66 (c) 64
  19. 19.A big cube of edge 8 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  20. 20.What is ∛6859? =
  21. 21.What is the smallest whole number by which 56 must be multiplied to get a perfect cube?
  22. 22.What is the smallest whole number by which 108 must be multiplied to get a perfect cube?
  23. 23.What is the smallest whole number by which 16 must be multiplied to get a perfect cube?
  24. 24.A big cube of edge 8 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  25. 25.What is the smallest whole number by which 1323 must be divided to get a perfect cube?
  26. 26.A cube has a volume of 27 cubic cm. How long is each edge (in cm)?
  27. 27.What is 9³? =
  28. 28.What is 7³? =
  29. 29.A big cube of edge 24 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  30. 30.A big cube of edge 3 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  31. 31.What is ∛9261? =
  32. 32.A big cube of edge 18 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  33. 33.What is ∛1331? =
  34. 34.What is the smallest whole number by which 432 must be multiplied to get a perfect cube?
  35. 35.What is 19³? =
  36. 36.A cube has a volume of 4096 cubic cm. How long is each edge (in cm)?
  37. 37.What is ∛5832? =
  38. 38.A big cube of edge 6 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  39. 39.A big cube of edge 12 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  40. 40.What is the smallest whole number by which 9 must be multiplied to get a perfect cube?

Answer key

  1. 125
  2. 11
  3. 25
  4. 25
  5. 10
  6. 17
  7. 4096
  8. 2
  9. 9
  10. 4
  11. 5
  12. 8
  13. 13
  14. 64
  15. 2197
  16. 5
  17. 14
  18. 64
  19. 8
  20. 19
  21. 49
  22. 2
  23. 4
  24. 64
  25. 49
  26. 3
  27. 729
  28. 343
  29. 216
  30. 27
  31. 21
  32. 216
  33. 11
  34. 4
  35. 6859
  36. 16
  37. 18
  38. 27
  39. 216
  40. 3

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