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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 893 · 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 17³? =
  2. 2.A big cube of edge 10 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  3. 3.Which of these is a perfect cube? (a) 838 (b) 729 (c) 785
  4. 4.What is the smallest whole number by which 2 must be multiplied to get a perfect cube?
  5. 5.What is the smallest whole number by which 192 must be divided to get a perfect cube?
  6. 6.Which of these is a perfect cube? (a) 97 (b) 64 (c) 71
  7. 7.A big cube of edge 8 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  8. 8.What is ∛27? =
  9. 9.What is the smallest whole number by which 24 must be divided to get a perfect cube?
  10. 10.A cube has a volume of 1000 cubic cm. How long is each edge (in cm)?
  11. 11.A cube has a volume of 729 cubic cm. How long is each edge (in cm)?
  12. 12.A cube has a volume of 5832 cubic cm. How long is each edge (in cm)?
  13. 13.What is 9³? =
  14. 14.What is ∛8? =
  15. 15.Which of these is a perfect cube? (a) 1766 (b) 2070 (c) 1728
  16. 16.What is 2³? =
  17. 17.What is 7³? =
  18. 18.What is ∛729? =
  19. 19.Which of these is a perfect cube? (a) 1621 (b) 1331 (c) 1394
  20. 20.What is ∛12167? =
  21. 21.Which of these is a perfect cube? (a) 145 (b) 125 (c) 137
  22. 22.What is the smallest whole number by which 432 must be multiplied to get a perfect cube?
  23. 23.Which of these is a perfect cube? (a) 278 (b) 226 (c) 216
  24. 24.A big cube of edge 2 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  25. 25.Which of these is a perfect cube? (a) 456 (b) 389 (c) 343
  26. 26.What is the smallest whole number by which 81 must be divided to get a perfect cube?
  27. 27.A cube has a volume of 4913 cubic cm. How long is each edge (in cm)?
  28. 28.A cube has a volume of 27 cubic cm. How long is each edge (in cm)?
  29. 29.A big cube of edge 6 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  30. 30.What is the smallest whole number by which 576 must be multiplied to get a perfect cube?
  31. 31.What is the smallest whole number by which 24 must be multiplied to get a perfect cube?
  32. 32.A cube has a volume of 343 cubic cm. How long is each edge (in cm)?
  33. 33.What is the smallest whole number by which 40 must be divided to get a perfect cube?
  34. 34.Which of these is a perfect cube? (a) 32 (b) 27 (c) 30
  35. 35.What is ∛5832? =
  36. 36.What is 4³? =
  37. 37.What is ∛1000? =
  38. 38.A cube has a volume of 4096 cubic cm. How long is each edge (in cm)?
  39. 39.What is 8³? =
  40. 40.What is ∛9261? =

Answer key

  1. 4913
  2. 125
  3. 729
  4. 4
  5. 3
  6. 64
  7. 8
  8. 3
  9. 3
  10. 10
  11. 9
  12. 18
  13. 729
  14. 2
  15. 1728
  16. 8
  17. 343
  18. 9
  19. 1331
  20. 23
  21. 125
  22. 4
  23. 216
  24. 8
  25. 343
  26. 3
  27. 17
  28. 3
  29. 8
  30. 3
  31. 9
  32. 7
  33. 5
  34. 27
  35. 18
  36. 64
  37. 10
  38. 16
  39. 512
  40. 21

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