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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 477 · 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 the smallest whole number by which 2 must be multiplied to get a perfect cube?
  2. 2.What is the smallest whole number by which 1080 must be divided to get a perfect cube?
  3. 3.A big cube of edge 5 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  4. 4.Which of these is a perfect cube? (a) 36 (b) 27 (c) 43
  5. 5.What is ∛6859? =
  6. 6.What is ∛5832? =
  7. 7.What is ∛3375? =
  8. 8.Which of these is a perfect cube? (a) 343 (b) 357 (c) 423
  9. 9.What is the smallest whole number by which 648 must be divided to get a perfect cube?
  10. 10.A big cube of edge 12 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  11. 11.A cube has a volume of 343 cubic cm. How long is each edge (in cm)?
  12. 12.What is 7³? =
  13. 13.What is the smallest whole number by which 256 must be divided to get a perfect cube?
  14. 14.A big cube of edge 4 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  15. 15.What is 12³? =
  16. 16.A big cube of edge 12 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  17. 17.What is the smallest whole number by which 3 must be multiplied to get a perfect cube?
  18. 18.Which of these is a perfect cube? (a) 512 (b) 542 (c) 592
  19. 19.Which of these is a perfect cube? (a) 2330 (b) 2259 (c) 2197
  20. 20.What is ∛216? =
  21. 21.What is 13³? =
  22. 22.Which of these is a perfect cube? (a) 318 (b) 291 (c) 216
  23. 23.What is the smallest whole number by which 5 must be divided to get a perfect cube?
  24. 24.Which of these is a perfect cube? (a) 3375 (b) 3675 (c) 3440
  25. 25.What is ∛15625? =
  26. 26.Which of these is a perfect cube? (a) 2744 (b) 2768 (c) 2783
  27. 27.What is ∛343? =
  28. 28.What is ∛4096? =
  29. 29.What is 5³? =
  30. 30.What is ∛4913? =
  31. 31.What is ∛512? =
  32. 32.A big cube of edge 6 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  33. 33.A big cube of edge 3 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  34. 34.What is the smallest whole number by which 192 must be multiplied to get a perfect cube?
  35. 35.Which of these is a perfect cube? (a) 1953 (b) 1728 (c) 2115
  36. 36.What is the smallest whole number by which 128 must be divided to get a perfect cube?
  37. 37.What is ∛125? =
  38. 38.Which of these is a perfect cube? (a) 125 (b) 142 (c) 160
  39. 39.A cube has a volume of 729 cubic cm. How long is each edge (in cm)?
  40. 40.What is 14³? =

Answer key

  1. 4
  2. 5
  3. 125
  4. 27
  5. 19
  6. 18
  7. 15
  8. 343
  9. 3
  10. 216
  11. 7
  12. 343
  13. 4
  14. 64
  15. 1728
  16. 27
  17. 9
  18. 512
  19. 2197
  20. 6
  21. 2197
  22. 216
  23. 5
  24. 3375
  25. 25
  26. 2744
  27. 7
  28. 16
  29. 125
  30. 17
  31. 8
  32. 27
  33. 27
  34. 9
  35. 1728
  36. 2
  37. 5
  38. 125
  39. 9
  40. 2744

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