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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 979 · 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 4 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  2. 2.What is 11³? =
  3. 3.What is ∛9261? =
  4. 4.What is 12³? =
  5. 5.What is the smallest whole number by which 675 must be divided to get a perfect cube?
  6. 6.A cube has a volume of 6859 cubic cm. How long is each edge (in cm)?
  7. 7.What is ∛10648? =
  8. 8.What is 2³? =
  9. 9.What is ∛729? =
  10. 10.A big cube of edge 5 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  11. 11.A cube has a volume of 1000 cubic cm. How long is each edge (in cm)?
  12. 12.A big cube of edge 10 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  13. 13.What is ∛8? =
  14. 14.What is the smallest whole number by which 3136 must be multiplied to get a perfect cube?
  15. 15.What is the smallest whole number by which 49 must be divided to get a perfect cube?
  16. 16.What is 9³? =
  17. 17.What is ∛2744? =
  18. 18.What is ∛125? =
  19. 19.Which of these is a perfect cube? (a) 3547 (b) 3929 (c) 3375
  20. 20.Which of these is a perfect cube? (a) 3282 (b) 2744 (c) 2803
  21. 21.Which of these is a perfect cube? (a) 74 (b) 76 (c) 64
  22. 22.Which of these is a perfect cube? (a) 1222 (b) 1000 (c) 1297
  23. 23.What is ∛512? =
  24. 24.What is ∛1728? =
  25. 25.What is ∛2197? =
  26. 26.What is 16³? =
  27. 27.What is ∛8000? =
  28. 28.What is the smallest whole number by which 32 must be divided to get a perfect cube?
  29. 29.A big cube of edge 8 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  30. 30.A big cube of edge 2 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  31. 31.What is the smallest whole number by which 3125 must be multiplied to get a perfect cube?
  32. 32.A big cube of edge 15 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  33. 33.What is the smallest whole number by which 864 must be divided to get a perfect cube?
  34. 34.What is the smallest whole number by which 128 must be multiplied to get a perfect cube?
  35. 35.What is ∛12167? =
  36. 36.A big cube of edge 16 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  37. 37.A big cube of edge 6 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  38. 38.Which of these is a perfect cube? (a) 125 (b) 191 (c) 172
  39. 39.A big cube of edge 24 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  40. 40.A cube has a volume of 343 cubic cm. How long is each edge (in cm)?

Answer key

  1. 64
  2. 1331
  3. 21
  4. 1728
  5. 25
  6. 19
  7. 22
  8. 8
  9. 9
  10. 125
  11. 10
  12. 125
  13. 2
  14. 7
  15. 49
  16. 729
  17. 14
  18. 5
  19. 3375
  20. 2744
  21. 64
  22. 1000
  23. 8
  24. 12
  25. 13
  26. 4096
  27. 20
  28. 4
  29. 8
  30. 8
  31. 5
  32. 125
  33. 4
  34. 4
  35. 23
  36. 64
  37. 216
  38. 125
  39. 216
  40. 7

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