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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 532 · 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 ∛15625? =
  2. 2.A cube has a volume of 2744 cubic cm. How long is each edge (in cm)?
  3. 3.What is ∛729? =
  4. 4.What is ∛4096? =
  5. 5.What is 11³? =
  6. 6.What is the smallest whole number by which 49 must be multiplied to get a perfect cube?
  7. 7.A big cube of edge 12 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  8. 8.What is the smallest whole number by which 2 must be divided to get a perfect cube?
  9. 9.Which of these is a perfect cube? (a) 390 (b) 343 (c) 460
  10. 10.Which of these is a perfect cube? (a) 930 (b) 729 (c) 923
  11. 11.A cube has a volume of 343 cubic cm. How long is each edge (in cm)?
  12. 12.What is ∛8? =
  13. 13.What is the smallest whole number by which 128 must be divided to get a perfect cube?
  14. 14.What is the smallest whole number by which 24 must be multiplied to get a perfect cube?
  15. 15.What is the smallest whole number by which 7 must be multiplied to get a perfect cube?
  16. 16.What is the smallest whole number by which 40 must be multiplied to get a perfect cube?
  17. 17.What is the smallest whole number by which 432 must be divided to get a perfect cube?
  18. 18.What is 19³? =
  19. 19.A cube has a volume of 125 cubic cm. How long is each edge (in cm)?
  20. 20.What is ∛5832? =
  21. 21.What is the smallest whole number by which 54 must be divided to get a perfect cube?
  22. 22.A big cube of edge 4 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  23. 23.What is ∛1728? =
  24. 24.What is the smallest whole number by which 192 must be multiplied to get a perfect cube?
  25. 25.What is the smallest whole number by which 56 must be multiplied to get a perfect cube?
  26. 26.A big cube of edge 8 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  27. 27.A big cube of edge 5 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  28. 28.Which of these is a perfect cube? (a) 1158 (b) 1000 (c) 1082
  29. 29.A big cube of edge 6 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  30. 30.A cube has a volume of 64 cubic cm. How long is each edge (in cm)?
  31. 31.What is ∛343? =
  32. 32.Which of these is a perfect cube? (a) 64 (b) 65 (c) 112
  33. 33.Which of these is a perfect cube? (a) 310 (b) 245 (c) 216
  34. 34.What is the smallest whole number by which 25 must be divided to get a perfect cube?
  35. 35.A cube has a volume of 3375 cubic cm. How long is each edge (in cm)?
  36. 36.A big cube of edge 24 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  37. 37.A big cube of edge 8 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  38. 38.What is 14³? =
  39. 39.Which of these is a perfect cube? (a) 125 (b) 186 (c) 147
  40. 40.Which of these is a perfect cube? (a) 512 (b) 531 (c) 671

Answer key

  1. 25
  2. 14
  3. 9
  4. 16
  5. 1331
  6. 7
  7. 64
  8. 2
  9. 343
  10. 729
  11. 7
  12. 2
  13. 2
  14. 9
  15. 49
  16. 25
  17. 2
  18. 6859
  19. 5
  20. 18
  21. 2
  22. 64
  23. 12
  24. 9
  25. 49
  26. 64
  27. 125
  28. 1000
  29. 216
  30. 4
  31. 7
  32. 64
  33. 216
  34. 25
  35. 15
  36. 216
  37. 8
  38. 2744
  39. 125
  40. 512

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