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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 631 · 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 25 must be multiplied to get a perfect cube?
  2. 2.What is the smallest whole number by which 576 must be multiplied to get a perfect cube?
  3. 3.What is the smallest whole number by which 7 must be divided to get a perfect cube?
  4. 4.A cube has a volume of 4913 cubic cm. How long is each edge (in cm)?
  5. 5.What is 16³? =
  6. 6.Which of these is a perfect cube? (a) 3375 (b) 3546 (c) 3494
  7. 7.What is 11³? =
  8. 8.A big cube of edge 16 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  9. 9.What is 15³? =
  10. 10.What is the smallest whole number by which 256 must be multiplied to get a perfect cube?
  11. 11.A cube has a volume of 125 cubic cm. How long is each edge (in cm)?
  12. 12.What is 6³? =
  13. 13.What is ∛512? =
  14. 14.What is 20³? =
  15. 15.What is the smallest whole number by which 49 must be divided to get a perfect cube?
  16. 16.A cube has a volume of 6859 cubic cm. How long is each edge (in cm)?
  17. 17.A cube has a volume of 1728 cubic cm. How long is each edge (in cm)?
  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.Which of these is a perfect cube? (a) 512 (b) 580 (c) 688
  20. 20.Which of these is a perfect cube? (a) 2197 (b) 2228 (c) 2244
  21. 21.What is 2³? =
  22. 22.A big cube of edge 4 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  23. 23.What is ∛343? =
  24. 24.What is the smallest whole number by which 1600 must be divided to get a perfect cube?
  25. 25.What is ∛12167? =
  26. 26.What is 5³? =
  27. 27.Which of these is a perfect cube? (a) 27 (b) 54 (c) 44
  28. 28.What is 12³? =
  29. 29.What is 13³? =
  30. 30.What is the smallest whole number by which 5400 must be multiplied to get a perfect cube?
  31. 31.A big cube of edge 3 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  32. 32.Which of these is a perfect cube? (a) 1728 (b) 2102 (c) 1924
  33. 33.What is 18³? =
  34. 34.What is ∛2197? =
  35. 35.A big cube of edge 18 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  36. 36.What is ∛1000? =
  37. 37.What is the smallest whole number by which 1080 must be multiplied to get a perfect cube?
  38. 38.What is 3³? =
  39. 39.What is the smallest whole number by which 675 must be divided to get a perfect cube?
  40. 40.What is 9³? =

Answer key

  1. 5
  2. 3
  3. 7
  4. 17
  5. 4096
  6. 3375
  7. 1331
  8. 64
  9. 3375
  10. 2
  11. 5
  12. 216
  13. 8
  14. 8000
  15. 49
  16. 19
  17. 12
  18. 125
  19. 512
  20. 2197
  21. 8
  22. 8
  23. 7
  24. 25
  25. 23
  26. 125
  27. 27
  28. 1728
  29. 2197
  30. 5
  31. 27
  32. 1728
  33. 5832
  34. 13
  35. 216
  36. 10
  37. 25
  38. 27
  39. 25
  40. 729

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