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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 160 · 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 320 must be multiplied to get a perfect cube?
  2. 2.Which of these is a perfect cube? (a) 512 (b) 696 (c) 635
  3. 3.A cube has a volume of 4096 cubic cm. How long is each edge (in cm)?
  4. 4.What is the smallest whole number by which 1080 must be divided to get a perfect cube?
  5. 5.A big cube of edge 16 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  6. 6.What is the smallest whole number by which 625 must be multiplied to get a perfect cube?
  7. 7.What is 12³? =
  8. 8.What is the smallest whole number by which 1125 must be multiplied to get a perfect cube?
  9. 9.What is ∛64? =
  10. 10.Which of these is a perfect cube? (a) 1132 (b) 1008 (c) 1000
  11. 11.A big cube of edge 9 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  12. 12.What is ∛9261? =
  13. 13.What is the smallest whole number by which 56 must be divided to get a perfect cube?
  14. 14.What is ∛8000? =
  15. 15.What is 11³? =
  16. 16.A big cube of edge 10 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  17. 17.A cube has a volume of 343 cubic cm. How long is each edge (in cm)?
  18. 18.What is ∛5832? =
  19. 19.What is 8³? =
  20. 20.What is 2³? =
  21. 21.Which of these is a perfect cube? (a) 470 (b) 486 (c) 343
  22. 22.A cube has a volume of 3375 cubic cm. How long is each edge (in cm)?
  23. 23.A cube has a volume of 8 cubic cm. How long is each edge (in cm)?
  24. 24.Which of these is a perfect cube? (a) 938 (b) 839 (c) 729
  25. 25.A cube has a volume of 64 cubic cm. How long is each edge (in cm)?
  26. 26.A big cube of edge 3 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  27. 27.Which of these is a perfect cube? (a) 1668 (b) 1580 (c) 1331
  28. 28.What is ∛1331? =
  29. 29.A cube has a volume of 6859 cubic cm. How long is each edge (in cm)?
  30. 30.What is 13³? =
  31. 31.What is 9³? =
  32. 32.What is the smallest whole number by which 375 must be multiplied to get a perfect cube?
  33. 33.What is the smallest whole number by which 16 must be divided to get a perfect cube?
  34. 34.What is the smallest whole number by which 72 must be multiplied to get a perfect cube?
  35. 35.A cube has a volume of 1728 cubic cm. How long is each edge (in cm)?
  36. 36.What is the smallest whole number by which 864 must be divided to get a perfect cube?
  37. 37.Which of these is a perfect cube? (a) 125 (b) 161 (c) 179
  38. 38.A big cube of edge 8 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  39. 39.What is the smallest whole number by which 3 must be divided to get a perfect cube?
  40. 40.A big cube of edge 4 cm is cut into small cubes of edge 2 cm. How many small cubes are there?

Answer key

  1. 25
  2. 512
  3. 16
  4. 5
  5. 64
  6. 25
  7. 1728
  8. 3
  9. 4
  10. 1000
  11. 27
  12. 21
  13. 7
  14. 20
  15. 1331
  16. 125
  17. 7
  18. 18
  19. 512
  20. 8
  21. 343
  22. 15
  23. 2
  24. 729
  25. 4
  26. 27
  27. 1331
  28. 11
  29. 19
  30. 2197
  31. 729
  32. 9
  33. 2
  34. 3
  35. 12
  36. 4
  37. 125
  38. 8
  39. 3
  40. 8

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