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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 699 · 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 ∛15625? =
  2. 2.What is the smallest whole number by which 250 must be divided to get a perfect cube?
  3. 3.What is ∛1331? =
  4. 4.What is ∛64? =
  5. 5.What is the smallest whole number by which 1125 must be divided to get a perfect cube?
  6. 6.What is 16³? =
  7. 7.What is 10³? =
  8. 8.Which of these is a perfect cube? (a) 27 (b) 49 (c) 30
  9. 9.A big cube of edge 6 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  10. 10.What is ∛4096? =
  11. 11.A big cube of edge 18 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  12. 12.A big cube of edge 5 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  13. 13.What is ∛125? =
  14. 14.What is the smallest whole number by which 40 must be multiplied to get a perfect cube?
  15. 15.A cube has a volume of 8 cubic cm. How long is each edge (in cm)?
  16. 16.What is 3³? =
  17. 17.What is the smallest whole number by which 392 must be multiplied to get a perfect cube?
  18. 18.What is the smallest whole number by which 32 must be multiplied to get a perfect cube?
  19. 19.What is the smallest whole number by which 81 must be divided to get a perfect cube?
  20. 20.A cube has a volume of 2744 cubic cm. How long is each edge (in cm)?
  21. 21.What is 19³? =
  22. 22.What is ∛9261? =
  23. 23.A cube has a volume of 27 cubic cm. How long is each edge (in cm)?
  24. 24.A cube has a volume of 2197 cubic cm. How long is each edge (in cm)?
  25. 25.Which of these is a perfect cube? (a) 2793 (b) 2744 (c) 3195
  26. 26.A big cube of edge 12 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  27. 27.What is 14³? =
  28. 28.What is the smallest whole number by which 3 must be divided to get a perfect cube?
  29. 29.What is the smallest whole number by which 3125 must be multiplied to get a perfect cube?
  30. 30.What is ∛343? =
  31. 31.What is 11³? =
  32. 32.A big cube of edge 6 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  33. 33.Which of these is a perfect cube? (a) 127 (b) 175 (c) 125
  34. 34.A cube has a volume of 64 cubic cm. How long is each edge (in cm)?
  35. 35.A big cube of edge 12 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  36. 36.A big cube of edge 3 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  37. 37.A cube has a volume of 5832 cubic cm. How long is each edge (in cm)?
  38. 38.Which of these is a perfect cube? (a) 551 (b) 512 (c) 673
  39. 39.A big cube of edge 16 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  40. 40.What is 9³? =

Answer key

  1. 25
  2. 2
  3. 11
  4. 4
  5. 9
  6. 4096
  7. 1000
  8. 27
  9. 8
  10. 16
  11. 216
  12. 125
  13. 5
  14. 25
  15. 2
  16. 27
  17. 7
  18. 2
  19. 3
  20. 14
  21. 6859
  22. 21
  23. 3
  24. 13
  25. 2744
  26. 216
  27. 2744
  28. 3
  29. 5
  30. 7
  31. 1331
  32. 27
  33. 125
  34. 4
  35. 27
  36. 27
  37. 18
  38. 512
  39. 64
  40. 729

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