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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 145 · 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 1080 must be divided to get a perfect cube?
  2. 2.What is ∛1728? =
  3. 3.A cube has a volume of 2197 cubic cm. How long is each edge (in cm)?
  4. 4.Which of these is a perfect cube? (a) 291 (b) 262 (c) 216
  5. 5.A cube has a volume of 2744 cubic cm. How long is each edge (in cm)?
  6. 6.A cube has a volume of 125 cubic cm. How long is each edge (in cm)?
  7. 7.What is ∛343? =
  8. 8.What is 15³? =
  9. 9.A big cube of edge 2 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  10. 10.What is the smallest whole number by which 3125 must be divided to get a perfect cube?
  11. 11.What is 14³? =
  12. 12.A cube has a volume of 343 cubic cm. How long is each edge (in cm)?
  13. 13.Which of these is a perfect cube? (a) 3146 (b) 2744 (c) 3043
  14. 14.A cube has a volume of 4096 cubic cm. How long is each edge (in cm)?
  15. 15.A big cube of edge 5 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  16. 16.A cube has a volume of 1331 cubic cm. How long is each edge (in cm)?
  17. 17.A cube has a volume of 8000 cubic cm. How long is each edge (in cm)?
  18. 18.What is ∛5832? =
  19. 19.What is the smallest whole number by which 128 must be multiplied to get a perfect cube?
  20. 20.What is the smallest whole number by which 5400 must be divided to get a perfect cube?
  21. 21.Which of these is a perfect cube? (a) 125 (b) 197 (c) 152
  22. 22.What is 2³? =
  23. 23.What is the smallest whole number by which 500 must be multiplied to get a perfect cube?
  24. 24.Which of these is a perfect cube? (a) 729 (b) 819 (c) 818
  25. 25.What is the smallest whole number by which 56 must be multiplied to get a perfect cube?
  26. 26.What is the smallest whole number by which 448 must be divided to get a perfect cube?
  27. 27.A big cube of edge 4 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  28. 28.A cube has a volume of 216 cubic cm. How long is each edge (in cm)?
  29. 29.A cube has a volume of 27 cubic cm. How long is each edge (in cm)?
  30. 30.What is the smallest whole number by which 7 must be divided to get a perfect cube?
  31. 31.Which of these is a perfect cube? (a) 2457 (b) 2197 (c) 2579
  32. 32.Which of these is a perfect cube? (a) 3377 (b) 3869 (c) 3375
  33. 33.What is the smallest whole number by which 392 must be divided to get a perfect cube?
  34. 34.A big cube of edge 15 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  35. 35.What is 17³? =
  36. 36.What is 5³? =
  37. 37.What is the smallest whole number by which 200 must be divided to get a perfect cube?
  38. 38.A cube has a volume of 64 cubic cm. How long is each edge (in cm)?
  39. 39.A cube has a volume of 8 cubic cm. How long is each edge (in cm)?
  40. 40.What is 19³? =

Answer key

  1. 5
  2. 12
  3. 13
  4. 216
  5. 14
  6. 5
  7. 7
  8. 3375
  9. 8
  10. 25
  11. 2744
  12. 7
  13. 2744
  14. 16
  15. 125
  16. 11
  17. 20
  18. 18
  19. 4
  20. 25
  21. 125
  22. 8
  23. 2
  24. 729
  25. 49
  26. 7
  27. 64
  28. 6
  29. 3
  30. 7
  31. 2197
  32. 3375
  33. 49
  34. 125
  35. 4913
  36. 125
  37. 25
  38. 4
  39. 2
  40. 6859

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