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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 791 · 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 192 must be divided to get a perfect cube?
  2. 2.What is the smallest whole number by which 40 must be multiplied to get a perfect cube?
  3. 3.A cube has a volume of 1728 cubic cm. How long is each edge (in cm)?
  4. 4.A cube has a volume of 1331 cubic cm. How long is each edge (in cm)?
  5. 5.A big cube of edge 4 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  6. 6.What is 18³? =
  7. 7.A cube has a volume of 8 cubic cm. How long is each edge (in cm)?
  8. 8.Which of these is a perfect cube? (a) 138 (b) 125 (c) 150
  9. 9.A cube has a volume of 343 cubic cm. How long is each edge (in cm)?
  10. 10.A big cube of edge 3 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  11. 11.What is the smallest whole number by which 7 must be divided to get a perfect cube?
  12. 12.What is the smallest whole number by which 32 must be divided to get a perfect cube?
  13. 13.What is the smallest whole number by which 3136 must be divided to get a perfect cube?
  14. 14.A big cube of edge 10 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  15. 15.What is 4³? =
  16. 16.What is 6³? =
  17. 17.What is 11³? =
  18. 18.What is the smallest whole number by which 864 must be divided to get a perfect cube?
  19. 19.Which of these is a perfect cube? (a) 47 (b) 40 (c) 27
  20. 20.Which of these is a perfect cube? (a) 246 (b) 216 (c) 236
  21. 21.What is ∛15625? =
  22. 22.What is ∛9261? =
  23. 23.A big cube of edge 8 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  24. 24.What is ∛2197? =
  25. 25.What is 5³? =
  26. 26.What is the smallest whole number by which 320 must be multiplied to get a perfect cube?
  27. 27.A cube has a volume of 3375 cubic cm. How long is each edge (in cm)?
  28. 28.A big cube of edge 6 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  29. 29.What is ∛216? =
  30. 30.What is 7³? =
  31. 31.Which of these is a perfect cube? (a) 2064 (b) 2126 (c) 1728
  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 16 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  34. 34.Which of these is a perfect cube? (a) 2668 (b) 2547 (c) 2197
  35. 35.A big cube of edge 18 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  36. 36.Which of these is a perfect cube? (a) 486 (b) 409 (c) 343
  37. 37.A cube has a volume of 64 cubic cm. How long is each edge (in cm)?
  38. 38.What is ∛8000? =
  39. 39.What is ∛5832? =
  40. 40.Which of these is a perfect cube? (a) 1384 (b) 1477 (c) 1331

Answer key

  1. 3
  2. 25
  3. 12
  4. 11
  5. 64
  6. 5832
  7. 2
  8. 125
  9. 7
  10. 27
  11. 7
  12. 4
  13. 49
  14. 125
  15. 64
  16. 216
  17. 1331
  18. 4
  19. 27
  20. 216
  21. 25
  22. 21
  23. 8
  24. 13
  25. 125
  26. 25
  27. 15
  28. 27
  29. 6
  30. 343
  31. 1728
  32. 8
  33. 64
  34. 2197
  35. 216
  36. 343
  37. 4
  38. 20
  39. 18
  40. 1331

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