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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 662 · 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 128 must be divided to get a perfect cube?
  2. 2.What is the smallest whole number by which 200 must be multiplied to get a perfect cube?
  3. 3.What is the smallest whole number by which 40 must be multiplied to get a perfect cube?
  4. 4.Which of these is a perfect cube? (a) 2647 (b) 2200 (c) 2197
  5. 5.Which of these is a perfect cube? (a) 1331 (b) 1572 (c) 1613
  6. 6.Which of these is a perfect cube? (a) 64 (b) 110 (c) 82
  7. 7.A big cube of edge 5 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  8. 8.What is the smallest whole number by which 5 must be divided to get a perfect cube?
  9. 9.A big cube of edge 3 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  10. 10.What is 9³? =
  11. 11.A cube has a volume of 216 cubic cm. How long is each edge (in cm)?
  12. 12.A big cube of edge 6 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  13. 13.What is 2³? =
  14. 14.A big cube of edge 2 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  15. 15.What is 4³? =
  16. 16.What is ∛125? =
  17. 17.What is 15³? =
  18. 18.A cube has a volume of 1331 cubic cm. How long is each edge (in cm)?
  19. 19.A big cube of edge 8 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  20. 20.What is ∛27? =
  21. 21.What is ∛729? =
  22. 22.What is 3³? =
  23. 23.What is 18³? =
  24. 24.What is the smallest whole number by which 192 must be divided to get a perfect cube?
  25. 25.Which of these is a perfect cube? (a) 1000 (b) 1193 (c) 1152
  26. 26.What is the smallest whole number by which 10584 must be multiplied to get a perfect cube?
  27. 27.What is 11³? =
  28. 28.A cube has a volume of 64 cubic cm. How long is each edge (in cm)?
  29. 29.A big cube of edge 16 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  30. 30.A cube has a volume of 5832 cubic cm. How long is each edge (in cm)?
  31. 31.What is 14³? =
  32. 32.Which of these is a perfect cube? (a) 410 (b) 343 (c) 370
  33. 33.What is the smallest whole number by which 6125 must be multiplied to get a perfect cube?
  34. 34.What is the smallest whole number by which 6125 must be divided to get a perfect cube?
  35. 35.What is ∛1728? =
  36. 36.What is ∛2744? =
  37. 37.What is the smallest whole number by which 24 must be divided to get a perfect cube?
  38. 38.What is 20³? =
  39. 39.A cube has a volume of 125 cubic cm. How long is each edge (in cm)?
  40. 40.What is the smallest whole number by which 108 must be divided to get a perfect cube?

Answer key

  1. 2
  2. 5
  3. 25
  4. 2197
  5. 1331
  6. 64
  7. 125
  8. 5
  9. 27
  10. 729
  11. 6
  12. 8
  13. 8
  14. 8
  15. 64
  16. 5
  17. 3375
  18. 11
  19. 8
  20. 3
  21. 9
  22. 27
  23. 5832
  24. 3
  25. 1000
  26. 7
  27. 1331
  28. 4
  29. 64
  30. 18
  31. 2744
  32. 343
  33. 7
  34. 49
  35. 12
  36. 14
  37. 3
  38. 8000
  39. 5
  40. 4

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