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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 787 · 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 32 must be divided to get a perfect cube?
  2. 2.What is ∛2197? =
  3. 3.What is 19³? =
  4. 4.A big cube of edge 6 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  5. 5.What is the smallest whole number by which 49 must be multiplied to get a perfect cube?
  6. 6.What is the smallest whole number by which 128 must be divided to get a perfect cube?
  7. 7.A cube has a volume of 125 cubic cm. How long is each edge (in cm)?
  8. 8.What is 16³? =
  9. 9.What is ∛2744? =
  10. 10.What is 3³? =
  11. 11.What is 11³? =
  12. 12.What is ∛216? =
  13. 13.A big cube of edge 16 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  14. 14.What is the smallest whole number by which 320 must be multiplied to get a perfect cube?
  15. 15.A big cube of edge 2 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  16. 16.Which of these is a perfect cube? (a) 343 (b) 432 (c) 406
  17. 17.What is the smallest whole number by which 7 must be multiplied to get a perfect cube?
  18. 18.A big cube of edge 3 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  19. 19.A big cube of edge 8 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  20. 20.What is ∛9261? =
  21. 21.Which of these is a perfect cube? (a) 1331 (b) 1413 (c) 1578
  22. 22.What is ∛125? =
  23. 23.What is the smallest whole number by which 49 must be divided to get a perfect cube?
  24. 24.What is 12³? =
  25. 25.Which of these is a perfect cube? (a) 3812 (b) 3951 (c) 3375
  26. 26.A big cube of edge 4 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  27. 27.What is 18³? =
  28. 28.What is the smallest whole number by which 81 must be divided to get a perfect cube?
  29. 29.A cube has a volume of 8 cubic cm. How long is each edge (in cm)?
  30. 30.A cube has a volume of 216 cubic cm. How long is each edge (in cm)?
  31. 31.What is 5³? =
  32. 32.A cube has a volume of 1000 cubic cm. How long is each edge (in cm)?
  33. 33.A big cube of edge 18 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  34. 34.What is 6³? =
  35. 35.A cube has a volume of 27 cubic cm. How long is each edge (in cm)?
  36. 36.A cube has a volume of 2744 cubic cm. How long is each edge (in cm)?
  37. 37.A cube has a volume of 4096 cubic cm. How long is each edge (in cm)?
  38. 38.What is the smallest whole number by which 4 must be divided to get a perfect cube?
  39. 39.What is 7³? =
  40. 40.What is ∛5832? =

Answer key

  1. 4
  2. 13
  3. 6859
  4. 27
  5. 7
  6. 2
  7. 5
  8. 4096
  9. 14
  10. 27
  11. 1331
  12. 6
  13. 64
  14. 25
  15. 8
  16. 343
  17. 49
  18. 27
  19. 64
  20. 21
  21. 1331
  22. 5
  23. 49
  24. 1728
  25. 3375
  26. 64
  27. 5832
  28. 3
  29. 2
  30. 6
  31. 125
  32. 10
  33. 216
  34. 216
  35. 3
  36. 14
  37. 16
  38. 4
  39. 343
  40. 18

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