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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 516 · 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 5 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  2. 2.What is ∛4096? =
  3. 3.What is the smallest whole number by which 448 must be divided to get a perfect cube?
  4. 4.Which of these is a perfect cube? (a) 1645 (b) 1556 (c) 1331
  5. 5.What is ∛8? =
  6. 6.What is the smallest whole number by which 32 must be divided to get a perfect cube?
  7. 7.What is 2³? =
  8. 8.What is ∛15625? =
  9. 9.What is 7³? =
  10. 10.A cube has a volume of 125 cubic cm. How long is each edge (in cm)?
  11. 11.A big cube of edge 10 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  12. 12.A cube has a volume of 8000 cubic cm. How long is each edge (in cm)?
  13. 13.What is the smallest whole number by which 189 must be divided to get a perfect cube?
  14. 14.What is ∛729? =
  15. 15.What is the smallest whole number by which 56 must be divided to get a perfect cube?
  16. 16.Which of these is a perfect cube? (a) 3283 (b) 2832 (c) 2744
  17. 17.A big cube of edge 4 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  18. 18.What is 14³? =
  19. 19.Which of these is a perfect cube? (a) 729 (b) 746 (c) 735
  20. 20.A big cube of edge 24 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  21. 21.A cube has a volume of 4913 cubic cm. How long is each edge (in cm)?
  22. 22.What is the smallest whole number by which 2 must be divided to get a perfect cube?
  23. 23.What is 19³? =
  24. 24.A big cube of edge 3 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  25. 25.What is the smallest whole number by which 675 must be divided to get a perfect cube?
  26. 26.What is ∛2744? =
  27. 27.What is 16³? =
  28. 28.What is 5³? =
  29. 29.What is ∛343? =
  30. 30.What is 8³? =
  31. 31.A big cube of edge 9 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  32. 32.What is 12³? =
  33. 33.What is ∛1331? =
  34. 34.Which of these is a perfect cube? (a) 240 (b) 230 (c) 216
  35. 35.Which of these is a perfect cube? (a) 128 (b) 169 (c) 125
  36. 36.Which of these is a perfect cube? (a) 98 (b) 106 (c) 64
  37. 37.A big cube of edge 6 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  38. 38.What is the smallest whole number by which 500 must be divided to get a perfect cube?
  39. 39.A cube has a volume of 8 cubic cm. How long is each edge (in cm)?
  40. 40.Which of these is a perfect cube? (a) 512 (b) 603 (c) 696

Answer key

  1. 125
  2. 16
  3. 7
  4. 1331
  5. 2
  6. 4
  7. 8
  8. 25
  9. 343
  10. 5
  11. 125
  12. 20
  13. 7
  14. 9
  15. 7
  16. 2744
  17. 64
  18. 2744
  19. 729
  20. 216
  21. 17
  22. 2
  23. 6859
  24. 27
  25. 25
  26. 14
  27. 4096
  28. 125
  29. 7
  30. 512
  31. 27
  32. 1728
  33. 11
  34. 216
  35. 125
  36. 64
  37. 27
  38. 4
  39. 2
  40. 512

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