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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 438 · 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 big cube of edge 4 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  2. 2.A big cube of edge 6 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  3. 3.Which of these is a perfect cube? (a) 343 (b) 393 (c) 366
  4. 4.A big cube of edge 8 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  5. 5.What is the smallest whole number by which 7 must be multiplied to get a perfect cube?
  6. 6.What is 7³? =
  7. 7.Which of these is a perfect cube? (a) 2764 (b) 2763 (c) 2744
  8. 8.What is ∛27? =
  9. 9.A cube has a volume of 6859 cubic cm. How long is each edge (in cm)?
  10. 10.A big cube of edge 6 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  11. 11.A cube has a volume of 8 cubic cm. How long is each edge (in cm)?
  12. 12.A cube has a volume of 512 cubic cm. How long is each edge (in cm)?
  13. 13.What is 12³? =
  14. 14.What is ∛1331? =
  15. 15.What is ∛3375? =
  16. 16.What is 9³? =
  17. 17.Which of these is a perfect cube? (a) 528 (b) 603 (c) 512
  18. 18.What is 2³? =
  19. 19.Which of these is a perfect cube? (a) 27 (b) 53 (c) 34
  20. 20.A big cube of edge 9 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  21. 21.What is 5³? =
  22. 22.Which of these is a perfect cube? (a) 1000 (b) 1141 (c) 1300
  23. 23.What is the smallest whole number by which 6125 must be multiplied to get a perfect cube?
  24. 24.What is 11³? =
  25. 25.What is 18³? =
  26. 26.A cube has a volume of 216 cubic cm. How long is each edge (in cm)?
  27. 27.What is the smallest whole number by which 3136 must be multiplied to get a perfect cube?
  28. 28.What is ∛216? =
  29. 29.Which of these is a perfect cube? (a) 3446 (b) 3909 (c) 3375
  30. 30.What is the smallest whole number by which 576 must be multiplied to get a perfect cube?
  31. 31.What is the smallest whole number by which 128 must be divided to get a perfect cube?
  32. 32.What is ∛10648? =
  33. 33.A cube has a volume of 729 cubic cm. How long is each edge (in cm)?
  34. 34.What is the smallest whole number by which 32 must be multiplied to get a perfect cube?
  35. 35.What is ∛729? =
  36. 36.What is 4³? =
  37. 37.A big cube of edge 3 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  38. 38.Which of these is a perfect cube? (a) 75 (b) 64 (c) 98
  39. 39.Which of these is a perfect cube? (a) 739 (b) 729 (c) 837
  40. 40.A cube has a volume of 1000 cubic cm. How long is each edge (in cm)?

Answer key

  1. 8
  2. 8
  3. 343
  4. 8
  5. 49
  6. 343
  7. 2744
  8. 3
  9. 19
  10. 216
  11. 2
  12. 8
  13. 1728
  14. 11
  15. 15
  16. 729
  17. 512
  18. 8
  19. 27
  20. 27
  21. 125
  22. 1000
  23. 7
  24. 1331
  25. 5832
  26. 6
  27. 7
  28. 6
  29. 3375
  30. 3
  31. 2
  32. 22
  33. 9
  34. 2
  35. 9
  36. 64
  37. 27
  38. 64
  39. 729
  40. 10

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