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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 738 · 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 9 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  2. 2.What is ∛15625? =
  3. 3.What is the smallest whole number by which 432 must be multiplied to get a perfect cube?
  4. 4.Which of these is a perfect cube? (a) 343 (b) 376 (c) 431
  5. 5.Which of these is a perfect cube? (a) 2388 (b) 2256 (c) 2197
  6. 6.A cube has a volume of 343 cubic cm. How long is each edge (in cm)?
  7. 7.What is ∛10648? =
  8. 8.Which of these is a perfect cube? (a) 1000 (b) 1009 (c) 1027
  9. 9.A big cube of edge 12 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  10. 10.Which of these is a perfect cube? (a) 285 (b) 216 (c) 270
  11. 11.A big cube of edge 8 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  12. 12.Which of these is a perfect cube? (a) 964 (b) 729 (c) 877
  13. 13.A cube has a volume of 1331 cubic cm. How long is each edge (in cm)?
  14. 14.A cube has a volume of 4096 cubic cm. How long is each edge (in cm)?
  15. 15.A big cube of edge 2 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  16. 16.Which of these is a perfect cube? (a) 1448 (b) 1672 (c) 1331
  17. 17.Which of these is a perfect cube? (a) 104 (b) 93 (c) 64
  18. 18.What is 8³? =
  19. 19.What is ∛3375? =
  20. 20.A big cube of edge 4 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  21. 21.What is ∛343? =
  22. 22.What is 3³? =
  23. 23.Which of these is a perfect cube? (a) 134 (b) 188 (c) 125
  24. 24.A cube has a volume of 27 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.What is ∛1331? =
  27. 27.A big cube of edge 18 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  28. 28.What is the smallest whole number by which 108 must be multiplied to get a perfect cube?
  29. 29.What is the smallest whole number by which 72 must be multiplied to get a perfect cube?
  30. 30.A cube has a volume of 2744 cubic cm. How long is each edge (in cm)?
  31. 31.What is the smallest whole number by which 576 must be divided to get a perfect cube?
  32. 32.What is the smallest whole number by which 54 must be multiplied to get a perfect cube?
  33. 33.What is ∛8000? =
  34. 34.What is 7³? =
  35. 35.What is ∛125? =
  36. 36.Which of these is a perfect cube? (a) 37 (b) 27 (c) 47
  37. 37.What is 15³? =
  38. 38.What is the smallest whole number by which 200 must be divided to get a perfect cube?
  39. 39.A cube has a volume of 512 cubic cm. How long is each edge (in cm)?
  40. 40.What is ∛512? =

Answer key

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

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