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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 914 · 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 7³? =
  2. 2.What is ∛9261? =
  3. 3.What is the smallest whole number by which 256 must be multiplied to get a perfect cube?
  4. 4.What is ∛15625? =
  5. 5.A big cube of edge 8 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  6. 6.A big cube of edge 3 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  7. 7.What is ∛1331? =
  8. 8.Which of these is a perfect cube? (a) 426 (b) 361 (c) 343
  9. 9.Which of these is a perfect cube? (a) 185 (b) 180 (c) 125
  10. 10.What is ∛2197? =
  11. 11.A cube has a volume of 2197 cubic cm. How long is each edge (in cm)?
  12. 12.A big cube of edge 4 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  13. 13.What is the smallest whole number by which 128 must be divided to get a perfect cube?
  14. 14.What is 18³? =
  15. 15.What is 4³? =
  16. 16.A big cube of edge 6 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  17. 17.What is ∛125? =
  18. 18.What is 2³? =
  19. 19.What is the smallest whole number by which 135 must be multiplied to get a perfect cube?
  20. 20.Which of these is a perfect cube? (a) 3375 (b) 3505 (c) 3800
  21. 21.Which of these is a perfect cube? (a) 28 (b) 27 (c) 33
  22. 22.What is 3³? =
  23. 23.Which of these is a perfect cube? (a) 1000 (b) 1252 (c) 1008
  24. 24.A cube has a volume of 4096 cubic cm. How long is each edge (in cm)?
  25. 25.A cube has a volume of 4913 cubic cm. How long is each edge (in cm)?
  26. 26.What is the smallest whole number by which 16 must be divided to get a perfect cube?
  27. 27.What is the smallest whole number by which 10584 must be divided to get a perfect cube?
  28. 28.Which of these is a perfect cube? (a) 3298 (b) 2744 (c) 2916
  29. 29.A cube has a volume of 27 cubic cm. How long is each edge (in cm)?
  30. 30.What is 6³? =
  31. 31.A cube has a volume of 512 cubic cm. How long is each edge (in cm)?
  32. 32.What is the smallest whole number by which 448 must be divided to get a perfect cube?
  33. 33.A big cube of edge 15 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  34. 34.What is 8³? =
  35. 35.A cube has a volume of 729 cubic cm. How long is each edge (in cm)?
  36. 36.Which of these is a perfect cube? (a) 316 (b) 216 (c) 292
  37. 37.What is the smallest whole number by which 49 must be divided to get a perfect cube?
  38. 38.What is the smallest whole number by which 32 must be multiplied to get a perfect cube?
  39. 39.What is 10³? =
  40. 40.Which of these is a perfect cube? (a) 2010 (b) 1728 (c) 1827

Answer key

  1. 343
  2. 21
  3. 2
  4. 25
  5. 8
  6. 27
  7. 11
  8. 343
  9. 125
  10. 13
  11. 13
  12. 8
  13. 2
  14. 5832
  15. 64
  16. 27
  17. 5
  18. 8
  19. 25
  20. 3375
  21. 27
  22. 27
  23. 1000
  24. 16
  25. 17
  26. 2
  27. 49
  28. 2744
  29. 3
  30. 216
  31. 8
  32. 7
  33. 125
  34. 512
  35. 9
  36. 216
  37. 49
  38. 2
  39. 1000
  40. 1728

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