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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 445 · 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.A big cube of edge 15 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  2. 2.A big cube of edge 18 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  3. 3.Which of these is a perfect cube? (a) 160 (b) 176 (c) 125
  4. 4.What is 5³? =
  5. 5.What is the smallest whole number by which 625 must be divided to get a perfect cube?
  6. 6.What is the smallest whole number by which 1125 must be divided to get a perfect cube?
  7. 7.A cube has a volume of 27 cubic cm. How long is each edge (in cm)?
  8. 8.A cube has a volume of 216 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 15³? =
  11. 11.Which of these is a perfect cube? (a) 679 (b) 516 (c) 512
  12. 12.What is 6³? =
  13. 13.Which of these is a perfect cube? (a) 968 (b) 754 (c) 729
  14. 14.Which of these is a perfect cube? (a) 1728 (b) 2131 (c) 1869
  15. 15.A big cube of edge 8 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  16. 16.Which of these is a perfect cube? (a) 463 (b) 361 (c) 343
  17. 17.Which of these is a perfect cube? (a) 27 (b) 50 (c) 29
  18. 18.A cube has a volume of 1000 cubic cm. How long is each edge (in cm)?
  19. 19.What is the smallest whole number by which 1600 must be divided to get a perfect cube?
  20. 20.What is ∛8000? =
  21. 21.What is 10³? =
  22. 22.What is 14³? =
  23. 23.A big cube of edge 6 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  24. 24.What is the smallest whole number by which 9 must be divided to get a perfect cube?
  25. 25.Which of these is a perfect cube? (a) 2272 (b) 2595 (c) 2197
  26. 26.What is 11³? =
  27. 27.What is the smallest whole number by which 25 must be multiplied to get a perfect cube?
  28. 28.What is 18³? =
  29. 29.A cube has a volume of 343 cubic cm. How long is each edge (in cm)?
  30. 30.Which of these is a perfect cube? (a) 110 (b) 106 (c) 64
  31. 31.What is ∛9261? =
  32. 32.What is ∛27? =
  33. 33.What is 19³? =
  34. 34.What is ∛5832? =
  35. 35.A big cube of edge 4 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  36. 36.A big cube of edge 10 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  37. 37.What is ∛1331? =
  38. 38.A big cube of edge 20 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  39. 39.What is 16³? =
  40. 40.Which of these is a perfect cube? (a) 2744 (b) 2773 (c) 3249

Answer key

  1. 125
  2. 216
  3. 125
  4. 125
  5. 5
  6. 9
  7. 3
  8. 6
  9. 64
  10. 3375
  11. 512
  12. 216
  13. 729
  14. 1728
  15. 8
  16. 343
  17. 27
  18. 10
  19. 25
  20. 20
  21. 1000
  22. 2744
  23. 27
  24. 9
  25. 2197
  26. 1331
  27. 5
  28. 5832
  29. 7
  30. 64
  31. 21
  32. 3
  33. 6859
  34. 18
  35. 8
  36. 125
  37. 11
  38. 125
  39. 4096
  40. 2744

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