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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 180 · 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 5³? =
  2. 2.What is ∛12167? =
  3. 3.What is the smallest whole number by which 49 must be multiplied to get a perfect cube?
  4. 4.What is 16³? =
  5. 5.What is 15³? =
  6. 6.What is ∛125? =
  7. 7.Which of these is a perfect cube? (a) 3375 (b) 3584 (c) 3874
  8. 8.What is the smallest whole number by which 7 must be divided to get a perfect cube?
  9. 9.What is ∛6859? =
  10. 10.A big cube of edge 2 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  11. 11.A big cube of edge 4 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  12. 12.Which of these is a perfect cube? (a) 104 (b) 96 (c) 64
  13. 13.What is ∛2744? =
  14. 14.What is the smallest whole number by which 1512 must be multiplied to get a perfect cube?
  15. 15.What is the smallest whole number by which 3 must be divided to get a perfect cube?
  16. 16.Which of these is a perfect cube? (a) 2893 (b) 3021 (c) 2744
  17. 17.What is ∛1728? =
  18. 18.A cube has a volume of 8000 cubic cm. How long is each edge (in cm)?
  19. 19.Which of these is a perfect cube? (a) 349 (b) 343 (c) 434
  20. 20.A cube has a volume of 3375 cubic cm. How long is each edge (in cm)?
  21. 21.What is 14³? =
  22. 22.What is the smallest whole number by which 9 must be divided to get a perfect cube?
  23. 23.What is ∛1331? =
  24. 24.What is ∛5832? =
  25. 25.What is the smallest whole number by which 1600 must be multiplied to get a perfect cube?
  26. 26.What is 3³? =
  27. 27.What is 9³? =
  28. 28.What is 17³? =
  29. 29.Which of these is a perfect cube? (a) 1291 (b) 1000 (c) 1222
  30. 30.A cube has a volume of 125 cubic cm. How long is each edge (in cm)?
  31. 31.Which of these is a perfect cube? (a) 151 (b) 125 (c) 149
  32. 32.What is ∛3375? =
  33. 33.Which of these is a perfect cube? (a) 702 (b) 609 (c) 512
  34. 34.What is 11³? =
  35. 35.A big cube of edge 8 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  36. 36.A cube has a volume of 512 cubic cm. How long is each edge (in cm)?
  37. 37.What is the smallest whole number by which 392 must be multiplied to get a perfect cube?
  38. 38.A cube has a volume of 2744 cubic cm. How long is each edge (in cm)?
  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 32 must be multiplied to get a perfect cube?

Answer key

  1. 125
  2. 23
  3. 7
  4. 4096
  5. 3375
  6. 5
  7. 3375
  8. 7
  9. 19
  10. 8
  11. 8
  12. 64
  13. 14
  14. 49
  15. 3
  16. 2744
  17. 12
  18. 20
  19. 343
  20. 15
  21. 2744
  22. 9
  23. 11
  24. 18
  25. 5
  26. 27
  27. 729
  28. 4913
  29. 1000
  30. 5
  31. 125
  32. 15
  33. 512
  34. 1331
  35. 64
  36. 8
  37. 7
  38. 14
  39. 2
  40. 2

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