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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 331 · 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 875 must be multiplied to get a perfect cube?
  2. 2.What is the smallest whole number by which 3 must be divided to get a perfect cube?
  3. 3.What is the smallest whole number by which 5 must be divided to get a perfect cube?
  4. 4.A big cube of edge 10 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  5. 5.What is ∛729? =
  6. 6.What is 11³? =
  7. 7.What is 18³? =
  8. 8.A big cube of edge 18 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  9. 9.A cube has a volume of 1331 cubic cm. How long is each edge (in cm)?
  10. 10.What is ∛125? =
  11. 11.A cube has a volume of 4096 cubic cm. How long is each edge (in cm)?
  12. 12.What is the smallest whole number by which 24 must be multiplied to get a perfect cube?
  13. 13.What is 8³? =
  14. 14.Which of these is a perfect cube? (a) 43 (b) 27 (c) 31
  15. 15.What is the smallest whole number by which 320 must be divided to get a perfect cube?
  16. 16.What is the smallest whole number by which 1944 must be multiplied to get a perfect cube?
  17. 17.What is 13³? =
  18. 18.What is the smallest whole number by which 576 must be multiplied to get a perfect cube?
  19. 19.What is 12³? =
  20. 20.What is the smallest whole number by which 864 must be divided to get a perfect cube?
  21. 21.Which of these is a perfect cube? (a) 674 (b) 700 (c) 512
  22. 22.Which of these is a perfect cube? (a) 3252 (b) 2744 (c) 2775
  23. 23.A big cube of edge 20 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  24. 24.Which of these is a perfect cube? (a) 1666 (b) 1331 (c) 1360
  25. 25.Which of these is a perfect cube? (a) 804 (b) 729 (c) 966
  26. 26.What is ∛216? =
  27. 27.What is 10³? =
  28. 28.What is the smallest whole number by which 1080 must be multiplied to get a perfect cube?
  29. 29.Which of these is a perfect cube? (a) 269 (b) 216 (c) 247
  30. 30.A big cube of edge 12 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  31. 31.What is 3³? =
  32. 32.A big cube of edge 4 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  33. 33.What is ∛4913? =
  34. 34.A big cube of edge 16 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  35. 35.What is 15³? =
  36. 36.A cube has a volume of 1000 cubic cm. How long is each edge (in cm)?
  37. 37.What is ∛64? =
  38. 38.What is 7³? =
  39. 39.A cube has a volume of 125 cubic cm. How long is each edge (in cm)?
  40. 40.A big cube of edge 2 cm is cut into small cubes of edge 1 cm. How many small cubes are there?

Answer key

  1. 49
  2. 3
  3. 5
  4. 125
  5. 9
  6. 1331
  7. 5832
  8. 216
  9. 11
  10. 5
  11. 16
  12. 9
  13. 512
  14. 27
  15. 5
  16. 3
  17. 2197
  18. 3
  19. 1728
  20. 4
  21. 512
  22. 2744
  23. 125
  24. 1331
  25. 729
  26. 6
  27. 1000
  28. 25
  29. 216
  30. 64
  31. 27
  32. 64
  33. 17
  34. 64
  35. 3375
  36. 10
  37. 4
  38. 343
  39. 5
  40. 8

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