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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 298 · 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 ∛13824? =
  2. 2.What is ∛125? =
  3. 3.A cube has a volume of 2744 cubic cm. How long is each edge (in cm)?
  4. 4.A cube has a volume of 343 cubic cm. How long is each edge (in cm)?
  5. 5.What is ∛2744? =
  6. 6.A big cube of edge 4 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  7. 7.A big cube of edge 24 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  8. 8.A big cube of edge 8 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  9. 9.What is ∛4913? =
  10. 10.Which of these is a perfect cube? (a) 1142 (b) 1218 (c) 1000
  11. 11.A big cube of edge 5 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  12. 12.A big cube of edge 12 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  13. 13.Which of these is a perfect cube? (a) 3832 (b) 3418 (c) 3375
  14. 14.A cube has a volume of 8000 cubic cm. How long is each edge (in cm)?
  15. 15.A big cube of edge 9 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  16. 16.What is 9³? =
  17. 17.What is 16³? =
  18. 18.A cube has a volume of 729 cubic cm. How long is each edge (in cm)?
  19. 19.What is 17³? =
  20. 20.Which of these is a perfect cube? (a) 27 (b) 35 (c) 54
  21. 21.What is ∛1331? =
  22. 22.What is 2³? =
  23. 23.What is the smallest whole number by which 320 must be multiplied to get a perfect cube?
  24. 24.What is 12³? =
  25. 25.Which of these is a perfect cube? (a) 576 (b) 512 (c) 687
  26. 26.What is the smallest whole number by which 500 must be multiplied to get a perfect cube?
  27. 27.A big cube of edge 3 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  28. 28.What is the smallest whole number by which 392 must be divided to get a perfect cube?
  29. 29.A cube has a volume of 4913 cubic cm. How long is each edge (in cm)?
  30. 30.Which of these is a perfect cube? (a) 1529 (b) 1575 (c) 1331
  31. 31.What is 13³? =
  32. 32.What is ∛216? =
  33. 33.A cube has a volume of 512 cubic cm. How long is each edge (in cm)?
  34. 34.What is the smallest whole number by which 40 must be multiplied to get a perfect cube?
  35. 35.Which of these is a perfect cube? (a) 185 (b) 163 (c) 125
  36. 36.A cube has a volume of 216 cubic cm. How long is each edge (in cm)?
  37. 37.Which of these is a perfect cube? (a) 2456 (b) 2197 (c) 2528
  38. 38.What is the smallest whole number by which 1512 must be multiplied to get a perfect cube?
  39. 39.What is the smallest whole number by which 448 must be divided to get a perfect cube?
  40. 40.What is the smallest whole number by which 81 must be multiplied to get a perfect cube?

Answer key

  1. 24
  2. 5
  3. 14
  4. 7
  5. 14
  6. 64
  7. 216
  8. 64
  9. 17
  10. 1000
  11. 125
  12. 27
  13. 3375
  14. 20
  15. 27
  16. 729
  17. 4096
  18. 9
  19. 4913
  20. 27
  21. 11
  22. 8
  23. 25
  24. 1728
  25. 512
  26. 2
  27. 27
  28. 49
  29. 17
  30. 1331
  31. 2197
  32. 6
  33. 8
  34. 25
  35. 125
  36. 6
  37. 2197
  38. 49
  39. 7
  40. 9

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