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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 682 · 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 ∛1000? =
  2. 2.What is ∛125? =
  3. 3.What is ∛5832? =
  4. 4.A cube has a volume of 4096 cubic cm. How long is each edge (in cm)?
  5. 5.What is 8³? =
  6. 6.A big cube of edge 6 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  7. 7.What is the smallest whole number by which 7 must be multiplied to get a perfect cube?
  8. 8.Which of these is a perfect cube? (a) 421 (b) 343 (c) 394
  9. 9.Which of these is a perfect cube? (a) 2148 (b) 1830 (c) 1728
  10. 10.What is the smallest whole number by which 5 must be divided to get a perfect cube?
  11. 11.What is the smallest whole number by which 1600 must be multiplied to get a perfect cube?
  12. 12.A big cube of edge 24 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  13. 13.A cube has a volume of 64 cubic cm. How long is each edge (in cm)?
  14. 14.What is the smallest whole number by which 1944 must be multiplied to get a perfect cube?
  15. 15.What is the smallest whole number by which 54 must be divided to get a perfect cube?
  16. 16.What is 17³? =
  17. 17.What is the smallest whole number by which 16 must be divided to get a perfect cube?
  18. 18.What is ∛8? =
  19. 19.What is 16³? =
  20. 20.Which of these is a perfect cube? (a) 91 (b) 90 (c) 64
  21. 21.What is ∛512? =
  22. 22.A cube has a volume of 8 cubic cm. How long is each edge (in cm)?
  23. 23.What is 10³? =
  24. 24.What is the smallest whole number by which 3125 must be multiplied to get a perfect cube?
  25. 25.What is 4³? =
  26. 26.What is ∛27? =
  27. 27.A cube has a volume of 2197 cubic cm. How long is each edge (in cm)?
  28. 28.What is 18³? =
  29. 29.What is 13³? =
  30. 30.Which of these is a perfect cube? (a) 176 (b) 125 (c) 135
  31. 31.What is the smallest whole number by which 49 must be divided to get a perfect cube?
  32. 32.Which of these is a perfect cube? (a) 1031 (b) 1000 (c) 1169
  33. 33.What is the smallest whole number by which 675 must be multiplied to get a perfect cube?
  34. 34.A cube has a volume of 1728 cubic cm. How long is each edge (in cm)?
  35. 35.A big cube of edge 2 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  36. 36.What is the smallest whole number by which 256 must be multiplied to get a perfect cube?
  37. 37.What is the smallest whole number by which 32 must be divided to get a perfect cube?
  38. 38.What is the smallest whole number by which 5 must be multiplied to get a perfect cube?
  39. 39.A cube has a volume of 6859 cubic cm. How long is each edge (in cm)?
  40. 40.What is the smallest whole number by which 32 must be multiplied to get a perfect cube?

Answer key

  1. 10
  2. 5
  3. 18
  4. 16
  5. 512
  6. 27
  7. 49
  8. 343
  9. 1728
  10. 5
  11. 5
  12. 216
  13. 4
  14. 3
  15. 2
  16. 4913
  17. 2
  18. 2
  19. 4096
  20. 64
  21. 8
  22. 2
  23. 1000
  24. 5
  25. 64
  26. 3
  27. 13
  28. 5832
  29. 2197
  30. 125
  31. 49
  32. 1000
  33. 5
  34. 12
  35. 8
  36. 2
  37. 4
  38. 25
  39. 19
  40. 2

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