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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 689 · 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.A cube has a volume of 1331 cubic cm. How long is each edge (in cm)?
  2. 2.What is ∛512? =
  3. 3.What is the smallest whole number by which 392 must be multiplied to get a perfect cube?
  4. 4.A cube has a volume of 729 cubic cm. How long is each edge (in cm)?
  5. 5.Which of these is a perfect cube? (a) 32 (b) 50 (c) 27
  6. 6.What is 16³? =
  7. 7.What is 11³? =
  8. 8.A cube has a volume of 6859 cubic cm. How long is each edge (in cm)?
  9. 9.What is ∛343? =
  10. 10.A cube has a volume of 1728 cubic cm. How long is each edge (in cm)?
  11. 11.A big cube of edge 6 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  12. 12.What is the smallest whole number by which 24 must be multiplied to get a perfect cube?
  13. 13.A cube has a volume of 512 cubic cm. How long is each edge (in cm)?
  14. 14.A big cube of edge 5 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  15. 15.What is 12³? =
  16. 16.What is the smallest whole number by which 4 must be divided to get a perfect cube?
  17. 17.Which of these is a perfect cube? (a) 512 (b) 656 (c) 553
  18. 18.Which of these is a perfect cube? (a) 75 (b) 112 (c) 64
  19. 19.What is 7³? =
  20. 20.What is ∛6859? =
  21. 21.A big cube of edge 6 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  22. 22.What is ∛9261? =
  23. 23.A big cube of edge 18 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  24. 24.What is 14³? =
  25. 25.What is 3³? =
  26. 26.What is 6³? =
  27. 27.What is the smallest whole number by which 675 must be multiplied to get a perfect cube?
  28. 28.What is 20³? =
  29. 29.A big cube of edge 2 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  30. 30.Which of these is a perfect cube? (a) 1217 (b) 1000 (c) 1257
  31. 31.What is ∛4096? =
  32. 32.A big cube of edge 9 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  33. 33.What is the smallest whole number by which 3125 must be multiplied to get a perfect cube?
  34. 34.A big cube of edge 12 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  35. 35.Which of these is a perfect cube? (a) 2757 (b) 2744 (c) 2791
  36. 36.Which of these is a perfect cube? (a) 2383 (b) 2494 (c) 2197
  37. 37.What is the smallest whole number by which 243 must be multiplied to get a perfect cube?
  38. 38.What is the smallest whole number by which 243 must be divided to get a perfect cube?
  39. 39.A big cube of edge 10 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 108 must be multiplied to get a perfect cube?

Answer key

  1. 11
  2. 8
  3. 7
  4. 9
  5. 27
  6. 4096
  7. 1331
  8. 19
  9. 7
  10. 12
  11. 216
  12. 9
  13. 8
  14. 125
  15. 1728
  16. 4
  17. 512
  18. 64
  19. 343
  20. 19
  21. 8
  22. 21
  23. 216
  24. 2744
  25. 27
  26. 216
  27. 5
  28. 8000
  29. 8
  30. 1000
  31. 16
  32. 27
  33. 5
  34. 27
  35. 2744
  36. 2197
  37. 3
  38. 9
  39. 125
  40. 2

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