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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 283 · 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 ∛9261? =
  2. 2.A cube has a volume of 1000 cubic cm. How long is each edge (in cm)?
  3. 3.A big cube of edge 3 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  4. 4.What is ∛8000? =
  5. 5.A big cube of edge 12 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  6. 6.What is ∛10648? =
  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.A cube has a volume of 343 cubic cm. How long is each edge (in cm)?
  9. 9.What is the smallest whole number by which 1944 must be divided to get a perfect cube?
  10. 10.What is the smallest whole number by which 128 must be divided to get a perfect cube?
  11. 11.Which of these is a perfect cube? (a) 939 (b) 729 (c) 935
  12. 12.What is 7³? =
  13. 13.Which of these is a perfect cube? (a) 3375 (b) 3432 (c) 3406
  14. 14.What is ∛343? =
  15. 15.Which of these is a perfect cube? (a) 1000 (b) 1149 (c) 1183
  16. 16.Which of these is a perfect cube? (a) 343 (b) 377 (c) 379
  17. 17.What is ∛1728? =
  18. 18.What is the smallest whole number by which 9 must be multiplied to get a perfect cube?
  19. 19.A big cube of edge 2 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  20. 20.What is 20³? =
  21. 21.A big cube of edge 12 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  22. 22.A cube has a volume of 6859 cubic cm. How long is each edge (in cm)?
  23. 23.Which of these is a perfect cube? (a) 1728 (b) 2003 (c) 1919
  24. 24.What is 15³? =
  25. 25.A cube has a volume of 8000 cubic cm. How long is each edge (in cm)?
  26. 26.What is the smallest whole number by which 2 must be divided to get a perfect cube?
  27. 27.What is ∛27? =
  28. 28.What is the smallest whole number by which 10584 must be multiplied to get a perfect cube?
  29. 29.What is 6³? =
  30. 30.What is ∛13824? =
  31. 31.Which of these is a perfect cube? (a) 659 (b) 575 (c) 512
  32. 32.What is 9³? =
  33. 33.What is the smallest whole number by which 1125 must be divided to get a perfect cube?
  34. 34.What is ∛2197? =
  35. 35.A big cube of edge 24 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  36. 36.A cube has a volume of 125 cubic cm. How long is each edge (in cm)?
  37. 37.A big cube of edge 6 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  38. 38.What is the smallest whole number by which 864 must be divided to get a perfect cube?
  39. 39.A big cube of edge 9 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  40. 40.What is ∛125? =

Answer key

  1. 21
  2. 10
  3. 27
  4. 20
  5. 27
  6. 22
  7. 216
  8. 7
  9. 9
  10. 2
  11. 729
  12. 343
  13. 3375
  14. 7
  15. 1000
  16. 343
  17. 12
  18. 3
  19. 8
  20. 8000
  21. 64
  22. 19
  23. 1728
  24. 3375
  25. 20
  26. 2
  27. 3
  28. 7
  29. 216
  30. 24
  31. 512
  32. 729
  33. 9
  34. 13
  35. 216
  36. 5
  37. 8
  38. 4
  39. 27
  40. 5

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