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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 19 · 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 cube has a volume of 2744 cubic cm. How long is each edge (in cm)?
  2. 2.What is 16³? =
  3. 3.What is the smallest whole number by which 3136 must be multiplied to get a perfect cube?
  4. 4.What is ∛8? =
  5. 5.What is 19³? =
  6. 6.What is the smallest whole number by which 1512 must be multiplied to get a perfect cube?
  7. 7.What is ∛125? =
  8. 8.A big cube of edge 20 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  9. 9.What is ∛15625? =
  10. 10.Which of these is a perfect cube? (a) 1084 (b) 1178 (c) 1000
  11. 11.What is the smallest whole number by which 1600 must be divided to get a perfect cube?
  12. 12.What is the smallest whole number by which 9 must be multiplied to get a perfect cube?
  13. 13.What is ∛27? =
  14. 14.What is ∛64? =
  15. 15.Which of these is a perfect cube? (a) 227 (b) 304 (c) 216
  16. 16.A big cube of edge 5 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  17. 17.What is 3³? =
  18. 18.What is ∛1331? =
  19. 19.What is 15³? =
  20. 20.A big cube of edge 6 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  21. 21.Which of these is a perfect cube? (a) 2197 (b) 2274 (c) 2378
  22. 22.What is 9³? =
  23. 23.Which of these is a perfect cube? (a) 447 (b) 438 (c) 343
  24. 24.What is the smallest whole number by which 54 must be multiplied to get a perfect cube?
  25. 25.What is 13³? =
  26. 26.What is ∛4096? =
  27. 27.A big cube of edge 4 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  28. 28.A big cube of edge 10 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  29. 29.What is 17³? =
  30. 30.A big cube of edge 8 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  31. 31.A big cube of edge 12 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  32. 32.What is 6³? =
  33. 33.What is ∛4913? =
  34. 34.Which of these is a perfect cube? (a) 3495 (b) 3639 (c) 3375
  35. 35.What is the smallest whole number by which 4 must be multiplied to get a perfect cube?
  36. 36.What is ∛512? =
  37. 37.What is the smallest whole number by which 135 must be multiplied to get a perfect cube?
  38. 38.A big cube of edge 6 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  39. 39.What is ∛6859? =
  40. 40.A big cube of edge 6 cm is cut into small cubes of edge 3 cm. How many small cubes are there?

Answer key

  1. 14
  2. 4096
  3. 7
  4. 2
  5. 6859
  6. 49
  7. 5
  8. 125
  9. 25
  10. 1000
  11. 25
  12. 3
  13. 3
  14. 4
  15. 216
  16. 125
  17. 27
  18. 11
  19. 3375
  20. 27
  21. 2197
  22. 729
  23. 343
  24. 4
  25. 2197
  26. 16
  27. 8
  28. 125
  29. 4913
  30. 64
  31. 216
  32. 216
  33. 17
  34. 3375
  35. 2
  36. 8
  37. 25
  38. 216
  39. 19
  40. 8

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