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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 307 · 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 27 cubic cm. How long is each edge (in cm)?
  2. 2.A big cube of edge 2 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  3. 3.What is the smallest whole number by which 1125 must be divided to get a perfect cube?
  4. 4.What is 3³? =
  5. 5.What is 12³? =
  6. 6.A big cube of edge 5 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  7. 7.Which of these is a perfect cube? (a) 2546 (b) 2197 (c) 2607
  8. 8.A big cube of edge 8 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  9. 9.A cube has a volume of 1000 cubic cm. How long is each edge (in cm)?
  10. 10.What is the smallest whole number by which 3136 must be divided to get a perfect cube?
  11. 11.Which of these is a perfect cube? (a) 160 (b) 138 (c) 125
  12. 12.What is ∛6859? =
  13. 13.What is ∛1000? =
  14. 14.What is the smallest whole number by which 432 must be divided to get a perfect cube?
  15. 15.What is ∛64? =
  16. 16.What is ∛9261? =
  17. 17.Which of these is a perfect cube? (a) 64 (b) 65 (c) 72
  18. 18.What is 8³? =
  19. 19.What is the smallest whole number by which 54 must be multiplied to get a perfect cube?
  20. 20.What is the smallest whole number by which 243 must be divided to get a perfect cube?
  21. 21.A big cube of edge 9 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  22. 22.Which of these is a perfect cube? (a) 316 (b) 216 (c) 227
  23. 23.What is the smallest whole number by which 32 must be multiplied to get a perfect cube?
  24. 24.Which of these is a perfect cube? (a) 1974 (b) 1757 (c) 1728
  25. 25.What is 5³? =
  26. 26.What is the smallest whole number by which 648 must be multiplied to get a perfect cube?
  27. 27.What is ∛3375? =
  28. 28.Which of these is a perfect cube? (a) 1331 (b) 1592 (c) 1528
  29. 29.A cube has a volume of 343 cubic cm. How long is each edge (in cm)?
  30. 30.What is ∛13824? =
  31. 31.What is ∛4913? =
  32. 32.What is 20³? =
  33. 33.What is the smallest whole number by which 1600 must be divided to get a perfect cube?
  34. 34.A cube has a volume of 8000 cubic cm. How long is each edge (in cm)?
  35. 35.What is the smallest whole number by which 4 must be multiplied to get a perfect cube?
  36. 36.What is the smallest whole number by which 7 must be multiplied to get a perfect cube?
  37. 37.What is ∛343? =
  38. 38.Which of these is a perfect cube? (a) 3161 (b) 2744 (c) 3325
  39. 39.What is ∛1728? =
  40. 40.What is the smallest whole number by which 128 must be divided to get a perfect cube?

Answer key

  1. 3
  2. 8
  3. 9
  4. 27
  5. 1728
  6. 125
  7. 2197
  8. 8
  9. 10
  10. 49
  11. 125
  12. 19
  13. 10
  14. 2
  15. 4
  16. 21
  17. 64
  18. 512
  19. 4
  20. 9
  21. 27
  22. 216
  23. 2
  24. 1728
  25. 125
  26. 9
  27. 15
  28. 1331
  29. 7
  30. 24
  31. 17
  32. 8000
  33. 25
  34. 20
  35. 2
  36. 49
  37. 7
  38. 2744
  39. 12
  40. 2

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