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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 974 · 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.Which of these is a perfect cube? (a) 762 (b) 904 (c) 729
  2. 2.What is 20³? =
  3. 3.Which of these is a perfect cube? (a) 42 (b) 35 (c) 27
  4. 4.What is ∛6859? =
  5. 5.What is the smallest whole number by which 375 must be divided to get a perfect cube?
  6. 6.Which of these is a perfect cube? (a) 2924 (b) 3281 (c) 2744
  7. 7.Which of these is a perfect cube? (a) 1682 (b) 1640 (c) 1331
  8. 8.Which of these is a perfect cube? (a) 613 (b) 574 (c) 512
  9. 9.A big cube of edge 12 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  10. 10.Which of these is a perfect cube? (a) 1000 (b) 1270 (c) 1010
  11. 11.A big cube of edge 12 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  12. 12.What is 6³? =
  13. 13.A big cube of edge 6 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  14. 14.What is 18³? =
  15. 15.What is 14³? =
  16. 16.What is ∛8? =
  17. 17.What is ∛15625? =
  18. 18.A cube has a volume of 125 cubic cm. How long is each edge (in cm)?
  19. 19.What is ∛2197? =
  20. 20.What is ∛125? =
  21. 21.A big cube of edge 6 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  22. 22.A cube has a volume of 27 cubic cm. How long is each edge (in cm)?
  23. 23.A cube has a volume of 8 cubic cm. How long is each edge (in cm)?
  24. 24.What is ∛512? =
  25. 25.A big cube of edge 2 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  26. 26.What is ∛729? =
  27. 27.What is 3³? =
  28. 28.Which of these is a perfect cube? (a) 178 (b) 141 (c) 125
  29. 29.What is the smallest whole number by which 1512 must be multiplied to get a perfect cube?
  30. 30.What is ∛27? =
  31. 31.What is the smallest whole number by which 49 must be multiplied to get a perfect cube?
  32. 32.What is 19³? =
  33. 33.Which of these is a perfect cube? (a) 3375 (b) 3458 (c) 4025
  34. 34.What is the smallest whole number by which 40 must be multiplied to get a perfect cube?
  35. 35.What is ∛12167? =
  36. 36.What is 5³? =
  37. 37.What is the smallest whole number by which 56 must be multiplied to get a perfect cube?
  38. 38.What is the smallest whole number by which 5 must be multiplied to get a perfect cube?
  39. 39.What is the smallest whole number by which 256 must be multiplied to get a perfect cube?
  40. 40.What is the smallest whole number by which 5400 must be multiplied to get a perfect cube?

Answer key

  1. 729
  2. 8000
  3. 27
  4. 19
  5. 3
  6. 2744
  7. 1331
  8. 512
  9. 27
  10. 1000
  11. 64
  12. 216
  13. 8
  14. 5832
  15. 2744
  16. 2
  17. 25
  18. 5
  19. 13
  20. 5
  21. 27
  22. 3
  23. 2
  24. 8
  25. 8
  26. 9
  27. 27
  28. 125
  29. 49
  30. 3
  31. 7
  32. 6859
  33. 3375
  34. 25
  35. 23
  36. 125
  37. 49
  38. 25
  39. 2
  40. 5

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