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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 52 · 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 9³? =
  2. 2.A big cube of edge 9 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  3. 3.A big cube of edge 8 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  4. 4.What is the smallest whole number by which 1323 must be multiplied to get a perfect cube?
  5. 5.A cube has a volume of 729 cubic cm. How long is each edge (in cm)?
  6. 6.What is ∛1331? =
  7. 7.A big cube of edge 8 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  8. 8.A cube has a volume of 216 cubic cm. How long is each edge (in cm)?
  9. 9.A cube has a volume of 5832 cubic cm. How long is each edge (in cm)?
  10. 10.What is 19³? =
  11. 11.Which of these is a perfect cube? (a) 3979 (b) 3716 (c) 3375
  12. 12.What is 11³? =
  13. 13.What is ∛9261? =
  14. 14.A cube has a volume of 8 cubic cm. How long is each edge (in cm)?
  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.What is ∛4913? =
  17. 17.A big cube of edge 6 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  18. 18.What is ∛512? =
  19. 19.Which of these is a perfect cube? (a) 216 (b) 274 (c) 243
  20. 20.What is ∛15625? =
  21. 21.What is ∛216? =
  22. 22.A cube has a volume of 2197 cubic cm. How long is each edge (in cm)?
  23. 23.A cube has a volume of 27 cubic cm. How long is each edge (in cm)?
  24. 24.A big cube of edge 6 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  25. 25.A big cube of edge 4 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  26. 26.What is the smallest whole number by which 25 must be multiplied to get a perfect cube?
  27. 27.What is the smallest whole number by which 2 must be multiplied to get a perfect cube?
  28. 28.Which of these is a perfect cube? (a) 29 (b) 46 (c) 27
  29. 29.What is ∛10648? =
  30. 30.What is the smallest whole number by which 1080 must be multiplied to get a perfect cube?
  31. 31.Which of these is a perfect cube? (a) 126 (b) 179 (c) 125
  32. 32.What is 16³? =
  33. 33.What is the smallest whole number by which 108 must be divided to get a perfect cube?
  34. 34.Which of these is a perfect cube? (a) 2781 (b) 2859 (c) 2744
  35. 35.What is ∛4096? =
  36. 36.What is ∛125? =
  37. 37.What is ∛2197? =
  38. 38.Which of these is a perfect cube? (a) 64 (b) 102 (c) 75
  39. 39.A cube has a volume of 125 cubic cm. How long is each edge (in cm)?
  40. 40.A cube has a volume of 512 cubic cm. How long is each edge (in cm)?

Answer key

  1. 729
  2. 27
  3. 8
  4. 7
  5. 9
  6. 11
  7. 64
  8. 6
  9. 18
  10. 6859
  11. 3375
  12. 1331
  13. 21
  14. 2
  15. 125
  16. 17
  17. 8
  18. 8
  19. 216
  20. 25
  21. 6
  22. 13
  23. 3
  24. 216
  25. 64
  26. 5
  27. 4
  28. 27
  29. 22
  30. 25
  31. 125
  32. 4096
  33. 4
  34. 2744
  35. 16
  36. 5
  37. 13
  38. 64
  39. 5
  40. 8

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