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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 989 · 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 1944 must be divided to get a perfect cube?
  2. 2.A big cube of edge 5 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  3. 3.A cube has a volume of 1000 cubic cm. How long is each edge (in cm)?
  4. 4.What is ∛9261? =
  5. 5.What is ∛4913? =
  6. 6.Which of these is a perfect cube? (a) 1619 (b) 1331 (c) 1682
  7. 7.Which of these is a perfect cube? (a) 1064 (b) 1223 (c) 1000
  8. 8.What is 16³? =
  9. 9.What is 6³? =
  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.A big cube of edge 2 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  12. 12.What is 9³? =
  13. 13.A cube has a volume of 5832 cubic cm. How long is each edge (in cm)?
  14. 14.What is ∛5832? =
  15. 15.What is the smallest whole number by which 243 must be divided to get a perfect cube?
  16. 16.Which of these is a perfect cube? (a) 3375 (b) 3566 (c) 3939
  17. 17.A big cube of edge 6 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  18. 18.What is the smallest whole number by which 2 must be divided to get a perfect cube?
  19. 19.A big cube of edge 4 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  20. 20.What is the smallest whole number by which 1080 must be multiplied to get a perfect cube?
  21. 21.What is ∛8? =
  22. 22.What is the smallest whole number by which 320 must be multiplied to get a perfect cube?
  23. 23.What is 15³? =
  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 32 must be divided to get a perfect cube?
  26. 26.Which of these is a perfect cube? (a) 403 (b) 465 (c) 343
  27. 27.A cube has a volume of 2197 cubic cm. How long is each edge (in cm)?
  28. 28.What is the smallest whole number by which 3125 must be divided to get a perfect cube?
  29. 29.Which of these is a perfect cube? (a) 40 (b) 29 (c) 27
  30. 30.What is the smallest whole number by which 128 must be multiplied to get a perfect cube?
  31. 31.What is 13³? =
  32. 32.A big cube of edge 8 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  33. 33.What is 18³? =
  34. 34.Which of these is a perfect cube? (a) 285 (b) 234 (c) 216
  35. 35.A cube has a volume of 343 cubic cm. How long is each edge (in cm)?
  36. 36.What is the smallest whole number by which 24 must be divided to get a perfect cube?
  37. 37.A cube has a volume of 8000 cubic cm. How long is each edge (in cm)?
  38. 38.Which of these is a perfect cube? (a) 2783 (b) 3168 (c) 2744
  39. 39.What is 14³? =
  40. 40.What is the smallest whole number by which 448 must be divided to get a perfect cube?

Answer key

  1. 9
  2. 125
  3. 10
  4. 21
  5. 17
  6. 1331
  7. 1000
  8. 4096
  9. 216
  10. 27
  11. 8
  12. 729
  13. 18
  14. 18
  15. 9
  16. 3375
  17. 216
  18. 2
  19. 8
  20. 25
  21. 2
  22. 25
  23. 3375
  24. 27
  25. 4
  26. 343
  27. 13
  28. 25
  29. 27
  30. 4
  31. 2197
  32. 64
  33. 5832
  34. 216
  35. 7
  36. 3
  37. 20
  38. 2744
  39. 2744
  40. 7

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