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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 793 · 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 the smallest whole number by which 6125 must be divided to get a perfect cube?
  2. 2.Which of these is a perfect cube? (a) 127 (b) 125 (c) 172
  3. 3.What is ∛125? =
  4. 4.What is 13³? =
  5. 5.What is 18³? =
  6. 6.A big cube of edge 2 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  7. 7.A big cube of edge 18 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  8. 8.What is the smallest whole number by which 16 must be divided to get a perfect cube?
  9. 9.What is 19³? =
  10. 10.A big cube of edge 6 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  11. 11.What is the smallest whole number by which 56 must be multiplied to get a perfect cube?
  12. 12.Which of these is a perfect cube? (a) 67 (b) 91 (c) 64
  13. 13.Which of these is a perfect cube? (a) 674 (b) 512 (c) 680
  14. 14.What is the smallest whole number by which 3125 must be multiplied to get a perfect cube?
  15. 15.What is 12³? =
  16. 16.Which of these is a perfect cube? (a) 3003 (b) 3040 (c) 2744
  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 ∛27? =
  19. 19.What is the smallest whole number by which 320 must be multiplied to get a perfect cube?
  20. 20.A cube has a volume of 5832 cubic cm. How long is each edge (in cm)?
  21. 21.Which of these is a perfect cube? (a) 293 (b) 313 (c) 216
  22. 22.What is the smallest whole number by which 128 must be divided to get a perfect cube?
  23. 23.A big cube of edge 4 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  24. 24.What is ∛5832? =
  25. 25.What is 5³? =
  26. 26.What is 16³? =
  27. 27.What is the smallest whole number by which 7 must be divided to get a perfect cube?
  28. 28.What is the smallest whole number by which 864 must be divided to get a perfect cube?
  29. 29.What is 7³? =
  30. 30.A cube has a volume of 64 cubic cm. How long is each edge (in cm)?
  31. 31.What is the smallest whole number by which 108 must be multiplied to get a perfect cube?
  32. 32.What is the smallest whole number by which 49 must be multiplied to get a perfect cube?
  33. 33.Which of these is a perfect cube? (a) 46 (b) 27 (c) 51
  34. 34.A cube has a volume of 27 cubic cm. How long is each edge (in cm)?
  35. 35.A cube has a volume of 8 cubic cm. How long is each edge (in cm)?
  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.What is ∛1728? =
  39. 39.A big cube of edge 12 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  40. 40.A big cube of edge 5 cm is cut into small cubes of edge 1 cm. How many small cubes are there?

Answer key

  1. 49
  2. 125
  3. 5
  4. 2197
  5. 5832
  6. 8
  7. 216
  8. 2
  9. 6859
  10. 27
  11. 49
  12. 64
  13. 512
  14. 5
  15. 1728
  16. 2744
  17. 8
  18. 3
  19. 25
  20. 18
  21. 216
  22. 2
  23. 64
  24. 18
  25. 125
  26. 4096
  27. 7
  28. 4
  29. 343
  30. 4
  31. 2
  32. 7
  33. 27
  34. 3
  35. 2
  36. 49
  37. 7
  38. 12
  39. 64
  40. 125

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