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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 123 · 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 9 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  2. 2.Which of these is a perfect cube? (a) 343 (b) 440 (c) 428
  3. 3.Which of these is a perfect cube? (a) 1000 (b) 1091 (c) 1192
  4. 4.What is ∛8? =
  5. 5.A big cube of edge 12 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  6. 6.What is the smallest whole number by which 1944 must be divided to get a perfect cube?
  7. 7.What is ∛64? =
  8. 8.Which of these is a perfect cube? (a) 32 (b) 50 (c) 27
  9. 9.A cube has a volume of 125 cubic cm. How long is each edge (in cm)?
  10. 10.A cube has a volume of 2197 cubic cm. How long is each edge (in cm)?
  11. 11.A big cube of edge 10 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  12. 12.What is ∛6859? =
  13. 13.What is the smallest whole number by which 189 must be multiplied to get a perfect cube?
  14. 14.What is 16³? =
  15. 15.Which of these is a perfect cube? (a) 1842 (b) 1783 (c) 1728
  16. 16.What is the smallest whole number by which 40 must be divided to get a perfect cube?
  17. 17.Which of these is a perfect cube? (a) 2301 (b) 2197 (c) 2343
  18. 18.What is 2³? =
  19. 19.What is the smallest whole number by which 5400 must be multiplied to get a perfect cube?
  20. 20.What is 8³? =
  21. 21.What is the smallest whole number by which 625 must be multiplied to get a perfect cube?
  22. 22.What is ∛8000? =
  23. 23.What is 12³? =
  24. 24.What is the smallest whole number by which 4 must be multiplied to get a perfect cube?
  25. 25.What is the smallest whole number by which 1323 must be divided to get a perfect cube?
  26. 26.What is ∛1331? =
  27. 27.A cube has a volume of 1331 cubic cm. How long is each edge (in cm)?
  28. 28.Which of these is a perfect cube? (a) 264 (b) 216 (c) 240
  29. 29.What is ∛5832? =
  30. 30.Which of these is a perfect cube? (a) 162 (b) 131 (c) 125
  31. 31.What is ∛15625? =
  32. 32.What is ∛216? =
  33. 33.A big cube of edge 15 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) 729 (b) 850 (c) 936
  35. 35.What is the smallest whole number by which 128 must be multiplied to get a perfect cube?
  36. 36.A big cube of edge 12 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  37. 37.A cube has a volume of 27 cubic cm. How long is each edge (in cm)?
  38. 38.A cube has a volume of 8 cubic cm. How long is each edge (in cm)?
  39. 39.Which of these is a perfect cube? (a) 102 (b) 64 (c) 108
  40. 40.What is 7³? =

Answer key

  1. 27
  2. 343
  3. 1000
  4. 2
  5. 64
  6. 9
  7. 4
  8. 27
  9. 5
  10. 13
  11. 125
  12. 19
  13. 49
  14. 4096
  15. 1728
  16. 5
  17. 2197
  18. 8
  19. 5
  20. 512
  21. 25
  22. 20
  23. 1728
  24. 2
  25. 49
  26. 11
  27. 11
  28. 216
  29. 18
  30. 125
  31. 25
  32. 6
  33. 125
  34. 729
  35. 4
  36. 216
  37. 3
  38. 2
  39. 64
  40. 343

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