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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 432 · 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 ∛10648? =
  2. 2.A cube has a volume of 343 cubic cm. How long is each edge (in cm)?
  3. 3.A cube has a volume of 6859 cubic cm. How long is each edge (in cm)?
  4. 4.What is ∛2744? =
  5. 5.What is the smallest whole number by which 200 must be multiplied to get a perfect cube?
  6. 6.A big cube of edge 20 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  7. 7.What is ∛125? =
  8. 8.A big cube of edge 9 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  9. 9.What is 6³? =
  10. 10.A big cube of edge 2 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  11. 11.What is 18³? =
  12. 12.A big cube of edge 6 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  13. 13.What is 19³? =
  14. 14.What is 3³? =
  15. 15.What is the smallest whole number by which 392 must be divided to get a perfect cube?
  16. 16.A cube has a volume of 2197 cubic cm. How long is each edge (in cm)?
  17. 17.A big cube of edge 10 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  18. 18.Which of these is a perfect cube? (a) 267 (b) 216 (c) 221
  19. 19.What is the smallest whole number by which 189 must be divided to get a perfect cube?
  20. 20.What is the smallest whole number by which 625 must be multiplied to get a perfect cube?
  21. 21.Which of these is a perfect cube? (a) 1940 (b) 2140 (c) 1728
  22. 22.What is the smallest whole number by which 5 must be multiplied to get a perfect cube?
  23. 23.What is ∛8000? =
  24. 24.What is the smallest whole number by which 648 must be multiplied to get a perfect cube?
  25. 25.A big cube of edge 8 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  26. 26.A cube has a volume of 512 cubic cm. How long is each edge (in cm)?
  27. 27.What is 16³? =
  28. 28.A big cube of edge 6 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  29. 29.What is the smallest whole number by which 4 must be divided to get a perfect cube?
  30. 30.What is 12³? =
  31. 31.What is 7³? =
  32. 32.What is the smallest whole number by which 243 must be divided to get a perfect cube?
  33. 33.What is the smallest whole number by which 32 must be divided to get a perfect cube?
  34. 34.What is ∛512? =
  35. 35.What is ∛1728? =
  36. 36.What is the smallest whole number by which 192 must be multiplied to get a perfect cube?
  37. 37.What is 10³? =
  38. 38.A big cube of edge 3 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  39. 39.What is ∛1000? =
  40. 40.Which of these is a perfect cube? (a) 2744 (b) 2786 (c) 3173

Answer key

  1. 22
  2. 7
  3. 19
  4. 14
  5. 5
  6. 125
  7. 5
  8. 27
  9. 216
  10. 8
  11. 5832
  12. 216
  13. 6859
  14. 27
  15. 49
  16. 13
  17. 125
  18. 216
  19. 7
  20. 25
  21. 1728
  22. 25
  23. 20
  24. 9
  25. 8
  26. 8
  27. 4096
  28. 8
  29. 4
  30. 1728
  31. 343
  32. 9
  33. 4
  34. 8
  35. 12
  36. 9
  37. 1000
  38. 27
  39. 10
  40. 2744

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