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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 380 · 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 875 must be multiplied to get a perfect cube?
  2. 2.What is 9³? =
  3. 3.What is ∛2744? =
  4. 4.A big cube of edge 18 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  5. 5.What is ∛12167? =
  6. 6.Which of these is a perfect cube? (a) 1347 (b) 1357 (c) 1331
  7. 7.A big cube of edge 4 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  8. 8.What is ∛1331? =
  9. 9.What is the smallest whole number by which 5400 must be divided to get a perfect cube?
  10. 10.What is 16³? =
  11. 11.A big cube of edge 12 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  12. 12.What is the smallest whole number by which 189 must be divided to get a perfect cube?
  13. 13.What is 20³? =
  14. 14.What is ∛125? =
  15. 15.A big cube of edge 8 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  16. 16.What is the smallest whole number by which 320 must be divided to get a perfect cube?
  17. 17.What is the smallest whole number by which 1080 must be multiplied to get a perfect cube?
  18. 18.What is ∛512? =
  19. 19.Which of these is a perfect cube? (a) 64 (b) 99 (c) 94
  20. 20.What is ∛1000? =
  21. 21.A cube has a volume of 6859 cubic cm. How long is each edge (in cm)?
  22. 22.A cube has a volume of 2744 cubic cm. How long is each edge (in cm)?
  23. 23.What is the smallest whole number by which 1125 must be multiplied to get a perfect cube?
  24. 24.What is 7³? =
  25. 25.What is ∛8? =
  26. 26.What is the smallest whole number by which 2 must be divided to get a perfect cube?
  27. 27.A big cube of edge 8 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  28. 28.What is the smallest whole number by which 1600 must be divided to get a perfect cube?
  29. 29.A big cube of edge 3 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  30. 30.What is the smallest whole number by which 200 must be multiplied to get a perfect cube?
  31. 31.What is ∛4096? =
  32. 32.What is the smallest whole number by which 250 must be multiplied to get a perfect cube?
  33. 33.What is the smallest whole number by which 72 must be multiplied to get a perfect cube?
  34. 34.Which of these is a perfect cube? (a) 3699 (b) 3495 (c) 3375
  35. 35.What is 3³? =
  36. 36.A cube has a volume of 64 cubic cm. How long is each edge (in cm)?
  37. 37.A cube has a volume of 5832 cubic cm. How long is each edge (in cm)?
  38. 38.Which of these is a perfect cube? (a) 462 (b) 343 (c) 453
  39. 39.Which of these is a perfect cube? (a) 125 (b) 173 (c) 189
  40. 40.What is 12³? =

Answer key

  1. 49
  2. 729
  3. 14
  4. 216
  5. 23
  6. 1331
  7. 64
  8. 11
  9. 25
  10. 4096
  11. 27
  12. 7
  13. 8000
  14. 5
  15. 64
  16. 5
  17. 25
  18. 8
  19. 64
  20. 10
  21. 19
  22. 14
  23. 3
  24. 343
  25. 2
  26. 2
  27. 8
  28. 25
  29. 27
  30. 5
  31. 16
  32. 4
  33. 3
  34. 3375
  35. 27
  36. 4
  37. 18
  38. 343
  39. 125
  40. 1728

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