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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 630 · 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 ∛1728? =
  2. 2.Which of these is a perfect cube? (a) 29 (b) 27 (c) 47
  3. 3.What is ∛1000? =
  4. 4.What is 17³? =
  5. 5.What is 15³? =
  6. 6.What is ∛5832? =
  7. 7.Which of these is a perfect cube? (a) 1386 (b) 1522 (c) 1331
  8. 8.A big cube of edge 12 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  9. 9.Which of these is a perfect cube? (a) 372 (b) 350 (c) 343
  10. 10.Which of these is a perfect cube? (a) 3797 (b) 3375 (c) 4002
  11. 11.A cube has a volume of 8000 cubic cm. How long is each edge (in cm)?
  12. 12.Which of these is a perfect cube? (a) 1000 (b) 1215 (c) 1102
  13. 13.A cube has a volume of 1000 cubic cm. How long is each edge (in cm)?
  14. 14.What is ∛216? =
  15. 15.What is the smallest whole number by which 432 must be multiplied to get a perfect cube?
  16. 16.Which of these is a perfect cube? (a) 2744 (b) 3034 (c) 2815
  17. 17.What is the smallest whole number by which 192 must be multiplied to get a perfect cube?
  18. 18.What is 20³? =
  19. 19.What is ∛125? =
  20. 20.A cube has a volume of 8 cubic cm. How long is each edge (in cm)?
  21. 21.What is 7³? =
  22. 22.A cube has a volume of 1728 cubic cm. How long is each edge (in cm)?
  23. 23.What is the smallest whole number by which 24 must be divided to get a perfect cube?
  24. 24.Which of these is a perfect cube? (a) 808 (b) 729 (c) 758
  25. 25.What is the smallest whole number by which 6125 must be multiplied to get a perfect cube?
  26. 26.A cube has a volume of 343 cubic cm. How long is each edge (in cm)?
  27. 27.What is 16³? =
  28. 28.A big cube of edge 3 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  29. 29.A big cube of edge 12 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  30. 30.A big cube of edge 8 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  31. 31.What is the smallest whole number by which 54 must be divided to get a perfect cube?
  32. 32.What is 18³? =
  33. 33.What is ∛4096? =
  34. 34.A big cube of edge 12 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  35. 35.What is 4³? =
  36. 36.A big cube of edge 20 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  37. 37.What is 3³? =
  38. 38.Which of these is a perfect cube? (a) 69 (b) 64 (c) 67
  39. 39.What is the smallest whole number by which 2 must be multiplied to get a perfect cube?
  40. 40.What is 2³? =

Answer key

  1. 12
  2. 27
  3. 10
  4. 4913
  5. 3375
  6. 18
  7. 1331
  8. 27
  9. 343
  10. 3375
  11. 20
  12. 1000
  13. 10
  14. 6
  15. 4
  16. 2744
  17. 9
  18. 8000
  19. 5
  20. 2
  21. 343
  22. 12
  23. 3
  24. 729
  25. 7
  26. 7
  27. 4096
  28. 27
  29. 216
  30. 8
  31. 2
  32. 5832
  33. 16
  34. 64
  35. 64
  36. 125
  37. 27
  38. 64
  39. 4
  40. 8

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