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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 634 · 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 16 must be multiplied to get a perfect cube?
  2. 2.What is the smallest whole number by which 24 must be multiplied to get a perfect cube?
  3. 3.A big cube of edge 4 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) 2208 (b) 2197 (c) 2441
  5. 5.What is the smallest whole number by which 250 must be multiplied to get a perfect cube?
  6. 6.What is ∛729? =
  7. 7.What is ∛6859? =
  8. 8.What is ∛2744? =
  9. 9.What is ∛216? =
  10. 10.A big cube of edge 5 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  11. 11.What is the smallest whole number by which 49 must be multiplied to get a perfect cube?
  12. 12.A big cube of edge 6 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  13. 13.What is the smallest whole number by which 9 must be divided to get a perfect cube?
  14. 14.A big cube of edge 12 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  15. 15.What is the smallest whole number by which 1944 must be divided to get a perfect cube?
  16. 16.What is ∛64? =
  17. 17.A cube has a volume of 6859 cubic cm. How long is each edge (in cm)?
  18. 18.What is the smallest whole number by which 625 must be multiplied to get a perfect cube?
  19. 19.Which of these is a perfect cube? (a) 610 (b) 512 (c) 557
  20. 20.What is 5³? =
  21. 21.Which of these is a perfect cube? (a) 105 (b) 84 (c) 64
  22. 22.A cube has a volume of 125 cubic cm. How long is each edge (in cm)?
  23. 23.What is 11³? =
  24. 24.What is 13³? =
  25. 25.A cube has a volume of 27 cubic cm. How long is each edge (in cm)?
  26. 26.A big cube of edge 3 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  27. 27.What is 15³? =
  28. 28.Which of these is a perfect cube? (a) 1682 (b) 1568 (c) 1331
  29. 29.Which of these is a perfect cube? (a) 29 (b) 27 (c) 31
  30. 30.A big cube of edge 16 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 3125 must be divided to get a perfect cube?
  32. 32.What is 19³? =
  33. 33.What is the smallest whole number by which 56 must be divided to get a perfect cube?
  34. 34.What is 8³? =
  35. 35.What is ∛4096? =
  36. 36.A cube has a volume of 1728 cubic cm. How long is each edge (in cm)?
  37. 37.A cube has a volume of 343 cubic cm. How long is each edge (in cm)?
  38. 38.What is 6³? =
  39. 39.What is ∛125? =
  40. 40.What is ∛4913? =

Answer key

  1. 4
  2. 9
  3. 64
  4. 2197
  5. 4
  6. 9
  7. 19
  8. 14
  9. 6
  10. 125
  11. 7
  12. 27
  13. 9
  14. 27
  15. 9
  16. 4
  17. 19
  18. 25
  19. 512
  20. 125
  21. 64
  22. 5
  23. 1331
  24. 2197
  25. 3
  26. 27
  27. 3375
  28. 1331
  29. 27
  30. 64
  31. 25
  32. 6859
  33. 7
  34. 512
  35. 16
  36. 12
  37. 7
  38. 216
  39. 5
  40. 17

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