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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 815 · 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 256 must be multiplied to get a perfect cube?
  2. 2.Which of these is a perfect cube? (a) 729 (b) 751 (c) 770
  3. 3.Which of these is a perfect cube? (a) 550 (b) 512 (c) 681
  4. 4.What is 16³? =
  5. 5.What is ∛8? =
  6. 6.What is the smallest whole number by which 3 must be multiplied to get a perfect cube?
  7. 7.What is 4³? =
  8. 8.A big cube of edge 12 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  9. 9.A cube has a volume of 729 cubic cm. How long is each edge (in cm)?
  10. 10.What is ∛1331? =
  11. 11.What is ∛1728? =
  12. 12.What is 13³? =
  13. 13.What is the smallest whole number by which 320 must be multiplied to get a perfect cube?
  14. 14.What is ∛216? =
  15. 15.Which of these is a perfect cube? (a) 3375 (b) 3376 (c) 3643
  16. 16.What is 2³? =
  17. 17.What is the smallest whole number by which 625 must be divided to get a perfect cube?
  18. 18.A big cube of edge 15 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  19. 19.A cube has a volume of 8000 cubic cm. How long is each edge (in cm)?
  20. 20.What is 20³? =
  21. 21.What is the smallest whole number by which 56 must be multiplied to get a perfect cube?
  22. 22.What is 5³? =
  23. 23.A big cube of edge 2 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  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.A cube has a volume of 2197 cubic cm. How long is each edge (in cm)?
  26. 26.What is 19³? =
  27. 27.What is ∛4913? =
  28. 28.Which of these is a perfect cube? (a) 1477 (b) 1641 (c) 1331
  29. 29.What is ∛8000? =
  30. 30.A cube has a volume of 1728 cubic cm. How long is each edge (in cm)?
  31. 31.What is ∛343? =
  32. 32.What is the smallest whole number by which 49 must be multiplied to get a perfect cube?
  33. 33.What is ∛2197? =
  34. 34.Which of these is a perfect cube? (a) 1943 (b) 1728 (c) 2111
  35. 35.What is ∛512? =
  36. 36.What is the smallest whole number by which 864 must be divided to get a perfect cube?
  37. 37.What is 14³? =
  38. 38.A big cube of edge 9 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  39. 39.A big cube of edge 12 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  40. 40.What is the smallest whole number by which 625 must be multiplied to get a perfect cube?

Answer key

  1. 2
  2. 729
  3. 512
  4. 4096
  5. 2
  6. 9
  7. 64
  8. 27
  9. 9
  10. 11
  11. 12
  12. 2197
  13. 25
  14. 6
  15. 3375
  16. 8
  17. 5
  18. 125
  19. 20
  20. 8000
  21. 49
  22. 125
  23. 8
  24. 27
  25. 13
  26. 6859
  27. 17
  28. 1331
  29. 20
  30. 12
  31. 7
  32. 7
  33. 13
  34. 1728
  35. 8
  36. 4
  37. 2744
  38. 27
  39. 64
  40. 25

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