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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 600 · 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.A big cube of edge 8 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  2. 2.What is the smallest whole number by which 25 must be divided to get a perfect cube?
  3. 3.What is ∛10648? =
  4. 4.What is the smallest whole number by which 32 must be divided to get a perfect cube?
  5. 5.What is the smallest whole number by which 54 must be multiplied to get a perfect cube?
  6. 6.What is ∛27? =
  7. 7.What is 19³? =
  8. 8.Which of these is a perfect cube? (a) 736 (b) 886 (c) 729
  9. 9.Which of these is a perfect cube? (a) 2697 (b) 2197 (c) 2634
  10. 10.A big cube of edge 8 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  11. 11.What is ∛9261? =
  12. 12.What is the smallest whole number by which 4 must be divided to get a perfect cube?
  13. 13.Which of these is a perfect cube? (a) 394 (b) 343 (c) 346
  14. 14.What is 20³? =
  15. 15.What is the smallest whole number by which 4 must be multiplied to get a perfect cube?
  16. 16.What is 11³? =
  17. 17.A big cube of edge 4 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  18. 18.What is 10³? =
  19. 19.A big cube of edge 4 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  20. 20.What is 6³? =
  21. 21.A big cube of edge 12 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  22. 22.A cube has a volume of 343 cubic cm. How long is each edge (in cm)?
  23. 23.A big cube of edge 12 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  24. 24.Which of these is a perfect cube? (a) 37 (b) 43 (c) 27
  25. 25.Which of these is a perfect cube? (a) 2744 (b) 2757 (c) 2946
  26. 26.What is 4³? =
  27. 27.A cube has a volume of 27 cubic cm. How long is each edge (in cm)?
  28. 28.Which of these is a perfect cube? (a) 188 (b) 179 (c) 125
  29. 29.A big cube of edge 5 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  30. 30.What is 16³? =
  31. 31.What is 3³? =
  32. 32.A big cube of edge 2 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  33. 33.A big cube of edge 6 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  34. 34.Which of these is a perfect cube? (a) 1094 (b) 1000 (c) 1129
  35. 35.What is the smallest whole number by which 24 must be multiplied to get a perfect cube?
  36. 36.Which of these is a perfect cube? (a) 592 (b) 512 (c) 580
  37. 37.A cube has a volume of 125 cubic cm. How long is each edge (in cm)?
  38. 38.What is the smallest whole number by which 10584 must be multiplied to get a perfect cube?
  39. 39.A cube has a volume of 1728 cubic cm. How long is each edge (in cm)?
  40. 40.What is 2³? =

Answer key

  1. 64
  2. 25
  3. 22
  4. 4
  5. 4
  6. 3
  7. 6859
  8. 729
  9. 2197
  10. 8
  11. 21
  12. 4
  13. 343
  14. 8000
  15. 2
  16. 1331
  17. 8
  18. 1000
  19. 64
  20. 216
  21. 216
  22. 7
  23. 27
  24. 27
  25. 2744
  26. 64
  27. 3
  28. 125
  29. 125
  30. 4096
  31. 27
  32. 8
  33. 8
  34. 1000
  35. 9
  36. 512
  37. 5
  38. 7
  39. 12
  40. 8

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