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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 549 · 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 20 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  2. 2.What is ∛1000? =
  3. 3.What is the smallest whole number by which 1512 must be divided to get a perfect cube?
  4. 4.What is 8³? =
  5. 5.A big cube of edge 4 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  6. 6.Which of these is a perfect cube? (a) 1556 (b) 1350 (c) 1331
  7. 7.A cube has a volume of 4096 cubic cm. How long is each edge (in cm)?
  8. 8.A big cube of edge 3 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  9. 9.What is 13³? =
  10. 10.What is 3³? =
  11. 11.What is the smallest whole number by which 243 must be multiplied to get a perfect cube?
  12. 12.Which of these is a perfect cube? (a) 65 (b) 90 (c) 64
  13. 13.What is 12³? =
  14. 14.A cube has a volume of 125 cubic cm. How long is each edge (in cm)?
  15. 15.What is the smallest whole number by which 625 must be multiplied to get a perfect cube?
  16. 16.What is the smallest whole number by which 864 must be multiplied to get a perfect cube?
  17. 17.Which of these is a perfect cube? (a) 1128 (b) 1000 (c) 1214
  18. 18.A big cube of edge 10 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  19. 19.What is the smallest whole number by which 392 must be multiplied to get a perfect cube?
  20. 20.What is the smallest whole number by which 5 must be multiplied to get a perfect cube?
  21. 21.What is the smallest whole number by which 648 must be multiplied to get a perfect cube?
  22. 22.Which of these is a perfect cube? (a) 888 (b) 747 (c) 729
  23. 23.What is the smallest whole number by which 4 must be divided to get a perfect cube?
  24. 24.What is the smallest whole number by which 10584 must be divided to get a perfect cube?
  25. 25.A cube has a volume of 512 cubic cm. How long is each edge (in cm)?
  26. 26.Which of these is a perfect cube? (a) 2197 (b) 2318 (c) 2434
  27. 27.A cube has a volume of 8 cubic cm. How long is each edge (in cm)?
  28. 28.A big cube of edge 9 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  29. 29.A cube has a volume of 729 cubic cm. How long is each edge (in cm)?
  30. 30.A cube has a volume of 5832 cubic cm. How long is each edge (in cm)?
  31. 31.What is 7³? =
  32. 32.What is 5³? =
  33. 33.A cube has a volume of 4913 cubic cm. How long is each edge (in cm)?
  34. 34.What is the smallest whole number by which 4 must be multiplied to get a perfect cube?
  35. 35.What is the smallest whole number by which 1512 must be multiplied to get a perfect cube?
  36. 36.A big cube of edge 6 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  37. 37.What is the smallest whole number by which 9 must be divided to get a perfect cube?
  38. 38.What is the smallest whole number by which 3125 must be multiplied to get a perfect cube?
  39. 39.What is ∛1728? =
  40. 40.What is ∛5832? =

Answer key

  1. 125
  2. 10
  3. 7
  4. 512
  5. 8
  6. 1331
  7. 16
  8. 27
  9. 2197
  10. 27
  11. 3
  12. 64
  13. 1728
  14. 5
  15. 25
  16. 2
  17. 1000
  18. 125
  19. 7
  20. 25
  21. 9
  22. 729
  23. 4
  24. 49
  25. 8
  26. 2197
  27. 2
  28. 27
  29. 9
  30. 18
  31. 343
  32. 125
  33. 17
  34. 2
  35. 49
  36. 27
  37. 9
  38. 5
  39. 12
  40. 18

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