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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 192 · 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 200 must be multiplied to get a perfect cube?
  2. 2.What is 15³? =
  3. 3.Which of these is a perfect cube? (a) 168 (b) 165 (c) 125
  4. 4.Which of these is a perfect cube? (a) 216 (b) 236 (c) 291
  5. 5.A cube has a volume of 8 cubic cm. How long is each edge (in cm)?
  6. 6.What is ∛27? =
  7. 7.Which of these is a perfect cube? (a) 1000 (b) 1147 (c) 1128
  8. 8.What is 5³? =
  9. 9.What is 2³? =
  10. 10.A big cube of edge 16 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  11. 11.What is 3³? =
  12. 12.What is ∛15625? =
  13. 13.Which of these is a perfect cube? (a) 1688 (b) 1447 (c) 1331
  14. 14.A cube has a volume of 216 cubic cm. How long is each edge (in cm)?
  15. 15.A big cube of edge 4 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  16. 16.A cube has a volume of 729 cubic cm. How long is each edge (in cm)?
  17. 17.What is 12³? =
  18. 18.Which of these is a perfect cube? (a) 343 (b) 389 (c) 457
  19. 19.Which of these is a perfect cube? (a) 2744 (b) 3299 (c) 2852
  20. 20.What is the smallest whole number by which 108 must be multiplied to get a perfect cube?
  21. 21.What is ∛729? =
  22. 22.A cube has a volume of 1331 cubic cm. How long is each edge (in cm)?
  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 11³? =
  25. 25.What is the smallest whole number by which 625 must be divided to get a perfect cube?
  26. 26.A cube has a volume of 125 cubic cm. How long is each edge (in cm)?
  27. 27.A big cube of edge 3 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  28. 28.What is the smallest whole number by which 875 must be multiplied to get a perfect cube?
  29. 29.A big cube of edge 10 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  30. 30.What is the smallest whole number by which 2 must be multiplied to get a perfect cube?
  31. 31.Which of these is a perfect cube? (a) 1771 (b) 1812 (c) 1728
  32. 32.What is ∛9261? =
  33. 33.What is 19³? =
  34. 34.What is the smallest whole number by which 7 must be divided to get a perfect cube?
  35. 35.A cube has a volume of 1728 cubic cm. How long is each edge (in cm)?
  36. 36.Which of these is a perfect cube? (a) 3750 (b) 3375 (c) 3760
  37. 37.What is ∛512? =
  38. 38.A big cube of edge 15 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 4 cm. How many small cubes are there?
  40. 40.A big cube of edge 12 cm is cut into small cubes of edge 3 cm. How many small cubes are there?

Answer key

  1. 5
  2. 3375
  3. 125
  4. 216
  5. 2
  6. 3
  7. 1000
  8. 125
  9. 8
  10. 64
  11. 27
  12. 25
  13. 1331
  14. 6
  15. 8
  16. 9
  17. 1728
  18. 343
  19. 2744
  20. 2
  21. 9
  22. 11
  23. 27
  24. 1331
  25. 5
  26. 5
  27. 27
  28. 49
  29. 125
  30. 4
  31. 1728
  32. 21
  33. 6859
  34. 7
  35. 12
  36. 3375
  37. 8
  38. 125
  39. 27
  40. 64

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