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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 342 · 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 40 must be multiplied to get a perfect cube?
  2. 2.What is ∛10648? =
  3. 3.What is the smallest whole number by which 32 must be divided to get a perfect cube?
  4. 4.A big cube of edge 6 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  5. 5.What is ∛1728? =
  6. 6.Which of these is a perfect cube? (a) 3648 (b) 3375 (c) 3486
  7. 7.A cube has a volume of 3375 cubic cm. How long is each edge (in cm)?
  8. 8.What is ∛2197? =
  9. 9.Which of these is a perfect cube? (a) 666 (b) 528 (c) 512
  10. 10.What is the smallest whole number by which 40 must be divided to get a perfect cube?
  11. 11.What is the smallest whole number by which 5 must be multiplied to get a perfect cube?
  12. 12.What is the smallest whole number by which 675 must be divided to get a perfect cube?
  13. 13.A cube has a volume of 1000 cubic cm. How long is each edge (in cm)?
  14. 14.What is 12³? =
  15. 15.What is 15³? =
  16. 16.What is 10³? =
  17. 17.A cube has a volume of 64 cubic cm. How long is each edge (in cm)?
  18. 18.A big cube of edge 20 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  19. 19.Which of these is a perfect cube? (a) 472 (b) 343 (c) 466
  20. 20.What is the smallest whole number by which 7 must be multiplied to get a perfect cube?
  21. 21.What is the smallest whole number by which 56 must be multiplied to get a perfect cube?
  22. 22.What is ∛1331? =
  23. 23.A cube has a volume of 4913 cubic cm. How long is each edge (in cm)?
  24. 24.Which of these is a perfect cube? (a) 2615 (b) 2197 (c) 2466
  25. 25.What is 5³? =
  26. 26.What is 3³? =
  27. 27.What is ∛64? =
  28. 28.What is the smallest whole number by which 5400 must be divided to get a perfect cube?
  29. 29.A cube has a volume of 6859 cubic cm. How long is each edge (in cm)?
  30. 30.A cube has a volume of 512 cubic cm. How long is each edge (in cm)?
  31. 31.What is ∛125? =
  32. 32.What is the smallest whole number by which 243 must be multiplied to get a perfect cube?
  33. 33.What is 11³? =
  34. 34.What is ∛343? =
  35. 35.What is 8³? =
  36. 36.A cube has a volume of 8 cubic cm. How long is each edge (in cm)?
  37. 37.A cube has a volume of 729 cubic cm. How long is each edge (in cm)?
  38. 38.What is ∛512? =
  39. 39.Which of these is a perfect cube? (a) 1580 (b) 1608 (c) 1331
  40. 40.A cube has a volume of 8000 cubic cm. How long is each edge (in cm)?

Answer key

  1. 25
  2. 22
  3. 4
  4. 8
  5. 12
  6. 3375
  7. 15
  8. 13
  9. 512
  10. 5
  11. 25
  12. 25
  13. 10
  14. 1728
  15. 3375
  16. 1000
  17. 4
  18. 125
  19. 343
  20. 49
  21. 49
  22. 11
  23. 17
  24. 2197
  25. 125
  26. 27
  27. 4
  28. 25
  29. 19
  30. 8
  31. 5
  32. 3
  33. 1331
  34. 7
  35. 512
  36. 2
  37. 9
  38. 8
  39. 1331
  40. 20

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