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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 804 · 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.Which of these is a perfect cube? (a) 147 (b) 171 (c) 125
  2. 2.What is 7³? =
  3. 3.A big cube of edge 6 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  4. 4.What is ∛2197? =
  5. 5.A big cube of edge 15 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  6. 6.What is ∛27? =
  7. 7.What is ∛216? =
  8. 8.What is 2³? =
  9. 9.What is ∛2744? =
  10. 10.What is the smallest whole number by which 108 must be divided to get a perfect cube?
  11. 11.What is ∛8000? =
  12. 12.Which of these is a perfect cube? (a) 1532 (b) 1331 (c) 1353
  13. 13.A cube has a volume of 343 cubic cm. How long is each edge (in cm)?
  14. 14.What is 11³? =
  15. 15.What is the smallest whole number by which 135 must be multiplied to get a perfect cube?
  16. 16.What is the smallest whole number by which 7 must be divided to get a perfect cube?
  17. 17.A big cube of edge 6 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  18. 18.A big cube of edge 12 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  19. 19.What is 16³? =
  20. 20.A big cube of edge 8 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  21. 21.Which of these is a perfect cube? (a) 1112 (b) 1060 (c) 1000
  22. 22.What is 6³? =
  23. 23.A big cube of edge 6 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  24. 24.What is ∛15625? =
  25. 25.Which of these is a perfect cube? (a) 818 (b) 900 (c) 729
  26. 26.What is the smallest whole number by which 128 must be multiplied to get a perfect cube?
  27. 27.What is 15³? =
  28. 28.A big cube of edge 2 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  29. 29.What is the smallest whole number by which 24 must be multiplied to get a perfect cube?
  30. 30.What is 8³? =
  31. 31.What is the smallest whole number by which 24 must be divided to get a perfect cube?
  32. 32.A cube has a volume of 27 cubic cm. How long is each edge (in cm)?
  33. 33.What is 10³? =
  34. 34.A cube has a volume of 512 cubic cm. How long is each edge (in cm)?
  35. 35.A cube has a volume of 8 cubic cm. How long is each edge (in cm)?
  36. 36.What is ∛12167? =
  37. 37.Which of these is a perfect cube? (a) 2197 (b) 2567 (c) 2216
  38. 38.What is 9³? =
  39. 39.Which of these is a perfect cube? (a) 84 (b) 64 (c) 68
  40. 40.What is the smallest whole number by which 448 must be multiplied to get a perfect cube?

Answer key

  1. 125
  2. 343
  3. 216
  4. 13
  5. 125
  6. 3
  7. 6
  8. 8
  9. 14
  10. 4
  11. 20
  12. 1331
  13. 7
  14. 1331
  15. 25
  16. 7
  17. 8
  18. 64
  19. 4096
  20. 64
  21. 1000
  22. 216
  23. 27
  24. 25
  25. 729
  26. 4
  27. 3375
  28. 8
  29. 9
  30. 512
  31. 3
  32. 3
  33. 1000
  34. 8
  35. 2
  36. 23
  37. 2197
  38. 729
  39. 64
  40. 49

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