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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 258 · 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 7³? =
  2. 2.What is 18³? =
  3. 3.What is 5³? =
  4. 4.What is the smallest whole number by which 375 must be multiplied to get a perfect cube?
  5. 5.A big cube of edge 2 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  6. 6.What is the smallest whole number by which 864 must be divided to get a perfect cube?
  7. 7.What is ∛216? =
  8. 8.A big cube of edge 6 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  9. 9.A big cube of edge 4 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  10. 10.Which of these is a perfect cube? (a) 190 (b) 180 (c) 125
  11. 11.A big cube of edge 16 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  12. 12.A big cube of edge 20 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  13. 13.What is the smallest whole number by which 1125 must be multiplied to get a perfect cube?
  14. 14.What is the smallest whole number by which 1944 must be divided to get a perfect cube?
  15. 15.A cube has a volume of 343 cubic cm. How long is each edge (in cm)?
  16. 16.Which of these is a perfect cube? (a) 2952 (b) 2744 (c) 3208
  17. 17.What is ∛27? =
  18. 18.Which of these is a perfect cube? (a) 343 (b) 428 (c) 488
  19. 19.What is the smallest whole number by which 5 must be multiplied to get a perfect cube?
  20. 20.A cube has a volume of 64 cubic cm. How long is each edge (in cm)?
  21. 21.A cube has a volume of 3375 cubic cm. How long is each edge (in cm)?
  22. 22.What is ∛729? =
  23. 23.What is 12³? =
  24. 24.A cube has a volume of 512 cubic cm. How long is each edge (in cm)?
  25. 25.What is 8³? =
  26. 26.What is ∛2197? =
  27. 27.What is ∛9261? =
  28. 28.What is ∛10648? =
  29. 29.What is 9³? =
  30. 30.Which of these is a perfect cube? (a) 268 (b) 281 (c) 216
  31. 31.What is ∛343? =
  32. 32.What is ∛512? =
  33. 33.What is the smallest whole number by which 81 must be divided to get a perfect cube?
  34. 34.What is 2³? =
  35. 35.What is 17³? =
  36. 36.What is ∛15625? =
  37. 37.What is ∛4913? =
  38. 38.What is the smallest whole number by which 648 must be multiplied to get a perfect cube?
  39. 39.A big cube of edge 24 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  40. 40.Which of these is a perfect cube? (a) 1100 (b) 1000 (c) 1226

Answer key

  1. 343
  2. 5832
  3. 125
  4. 9
  5. 8
  6. 4
  7. 6
  8. 8
  9. 64
  10. 125
  11. 64
  12. 125
  13. 3
  14. 9
  15. 7
  16. 2744
  17. 3
  18. 343
  19. 25
  20. 4
  21. 15
  22. 9
  23. 1728
  24. 8
  25. 512
  26. 13
  27. 21
  28. 22
  29. 729
  30. 216
  31. 7
  32. 8
  33. 3
  34. 8
  35. 4913
  36. 25
  37. 17
  38. 9
  39. 216
  40. 1000

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