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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 720 · 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 12 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  2. 2.What is the smallest whole number by which 24 must be multiplied to get a perfect cube?
  3. 3.A cube has a volume of 64 cubic cm. How long is each edge (in cm)?
  4. 4.A big cube of edge 8 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  5. 5.Which of these is a perfect cube? (a) 1425 (b) 1331 (c) 1426
  6. 6.What is ∛10648? =
  7. 7.What is the smallest whole number by which 4 must be multiplied to get a perfect cube?
  8. 8.A big cube of edge 6 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  9. 9.What is the smallest whole number by which 1323 must be multiplied to get a perfect cube?
  10. 10.Which of these is a perfect cube? (a) 27 (b) 40 (c) 39
  11. 11.What is the smallest whole number by which 3 must be multiplied to get a perfect cube?
  12. 12.What is the smallest whole number by which 6125 must be divided to get a perfect cube?
  13. 13.What is ∛1331? =
  14. 14.What is 16³? =
  15. 15.A big cube of edge 6 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  16. 16.What is ∛6859? =
  17. 17.What is the smallest whole number by which 6125 must be multiplied to get a perfect cube?
  18. 18.A big cube of edge 4 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  19. 19.A big cube of edge 18 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  20. 20.What is 7³? =
  21. 21.A cube has a volume of 1331 cubic cm. How long is each edge (in cm)?
  22. 22.What is ∛216? =
  23. 23.What is the smallest whole number by which 1512 must be multiplied to get a perfect cube?
  24. 24.A cube has a volume of 1000 cubic cm. How long is each edge (in cm)?
  25. 25.A cube has a volume of 216 cubic cm. How long is each edge (in cm)?
  26. 26.Which of these is a perfect cube? (a) 963 (b) 729 (c) 885
  27. 27.What is ∛12167? =
  28. 28.A cube has a volume of 2197 cubic cm. How long is each edge (in cm)?
  29. 29.What is the smallest whole number by which 1125 must be divided to get a perfect cube?
  30. 30.Which of these is a perfect cube? (a) 378 (b) 433 (c) 343
  31. 31.What is the smallest whole number by which 1944 must be divided to get a perfect cube?
  32. 32.What is 4³? =
  33. 33.What is the smallest whole number by which 32 must be divided to get a perfect cube?
  34. 34.What is 5³? =
  35. 35.Which of these is a perfect cube? (a) 2306 (b) 2197 (c) 2297
  36. 36.What is the smallest whole number by which 24 must be divided to get a perfect cube?
  37. 37.What is the smallest whole number by which 432 must be divided to get a perfect cube?
  38. 38.A big cube of edge 12 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  39. 39.What is the smallest whole number by which 16 must be multiplied to get a perfect cube?
  40. 40.A cube has a volume of 125 cubic cm. How long is each edge (in cm)?

Answer key

  1. 64
  2. 9
  3. 4
  4. 8
  5. 1331
  6. 22
  7. 2
  8. 216
  9. 7
  10. 27
  11. 9
  12. 49
  13. 11
  14. 4096
  15. 8
  16. 19
  17. 7
  18. 8
  19. 216
  20. 343
  21. 11
  22. 6
  23. 49
  24. 10
  25. 6
  26. 729
  27. 23
  28. 13
  29. 9
  30. 343
  31. 9
  32. 64
  33. 4
  34. 125
  35. 2197
  36. 3
  37. 2
  38. 216
  39. 4
  40. 5

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