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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 333 · 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 189 must be divided to get a perfect cube?
  2. 2.What is 4³? =
  3. 3.What is ∛343? =
  4. 4.What is the smallest whole number by which 1080 must be multiplied to get a perfect cube?
  5. 5.Which of these is a perfect cube? (a) 972 (b) 790 (c) 729
  6. 6.What is ∛512? =
  7. 7.What is 20³? =
  8. 8.A cube has a volume of 8000 cubic cm. How long is each edge (in cm)?
  9. 9.A big cube of edge 8 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  10. 10.What is the smallest whole number by which 875 must be multiplied to get a perfect cube?
  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.A big cube of edge 4 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  13. 13.What is 6³? =
  14. 14.What is the smallest whole number by which 3136 must be divided to get a perfect cube?
  15. 15.What is the smallest whole number by which 2 must be divided to get a perfect cube?
  16. 16.A big cube of edge 5 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  17. 17.What is ∛729? =
  18. 18.What is 9³? =
  19. 19.What is the smallest whole number by which 250 must be multiplied to get a perfect cube?
  20. 20.What is the smallest whole number by which 16 must be multiplied to get a perfect cube?
  21. 21.What is ∛6859? =
  22. 22.What is the smallest whole number by which 448 must be divided to get a perfect cube?
  23. 23.What is 18³? =
  24. 24.What is 7³? =
  25. 25.What is 14³? =
  26. 26.A big cube of edge 8 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  27. 27.Which of these is a perfect cube? (a) 554 (b) 628 (c) 512
  28. 28.A cube has a volume of 216 cubic cm. How long is each edge (in cm)?
  29. 29.A big cube of edge 6 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  30. 30.Which of these is a perfect cube? (a) 1331 (b) 1350 (c) 1492
  31. 31.Which of these is a perfect cube? (a) 216 (b) 222 (c) 298
  32. 32.What is ∛125? =
  33. 33.What is the smallest whole number by which 200 must be divided to get a perfect cube?
  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.A cube has a volume of 1728 cubic cm. How long is each edge (in cm)?
  36. 36.What is the smallest whole number by which 10584 must be divided to get a perfect cube?
  37. 37.A cube has a volume of 27 cubic cm. How long is each edge (in cm)?
  38. 38.Which of these is a perfect cube? (a) 4007 (b) 3594 (c) 3375
  39. 39.A cube has a volume of 729 cubic cm. How long is each edge (in cm)?
  40. 40.Which of these is a perfect cube? (a) 27 (b) 43 (c) 40

Answer key

  1. 7
  2. 64
  3. 7
  4. 25
  5. 729
  6. 8
  7. 8000
  8. 20
  9. 64
  10. 49
  11. 8
  12. 64
  13. 216
  14. 49
  15. 2
  16. 125
  17. 9
  18. 729
  19. 4
  20. 4
  21. 19
  22. 7
  23. 5832
  24. 343
  25. 2744
  26. 8
  27. 512
  28. 6
  29. 216
  30. 1331
  31. 216
  32. 5
  33. 25
  34. 64
  35. 12
  36. 49
  37. 3
  38. 3375
  39. 9
  40. 27

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