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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 152 · 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 128 must be multiplied to get a perfect cube?
  2. 2.What is the smallest whole number by which 625 must be multiplied to get a perfect cube?
  3. 3.What is ∛2197? =
  4. 4.What is the smallest whole number by which 648 must be multiplied to get a perfect cube?
  5. 5.Which of these is a perfect cube? (a) 3375 (b) 3720 (c) 3445
  6. 6.A big cube of edge 6 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  7. 7.What is the smallest whole number by which 192 must be multiplied to get a perfect cube?
  8. 8.A cube has a volume of 1000 cubic cm. How long is each edge (in cm)?
  9. 9.What is the smallest whole number by which 1944 must be divided to get a perfect cube?
  10. 10.What is 7³? =
  11. 11.What is the smallest whole number by which 875 must be multiplied to get a perfect cube?
  12. 12.A big cube of edge 3 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  13. 13.What is ∛4913? =
  14. 14.What is ∛9261? =
  15. 15.A cube has a volume of 4096 cubic cm. How long is each edge (in cm)?
  16. 16.A cube has a volume of 216 cubic cm. How long is each edge (in cm)?
  17. 17.What is 17³? =
  18. 18.A big cube of edge 20 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  19. 19.What is 13³? =
  20. 20.What is the smallest whole number by which 1512 must be divided to get a perfect cube?
  21. 21.What is ∛1000? =
  22. 22.What is ∛13824? =
  23. 23.What is the smallest whole number by which 1512 must be multiplied to get a perfect cube?
  24. 24.What is 9³? =
  25. 25.What is ∛4096? =
  26. 26.What is ∛8? =
  27. 27.A cube has a volume of 1728 cubic cm. How long is each edge (in cm)?
  28. 28.Which of these is a perfect cube? (a) 1331 (b) 1431 (c) 1410
  29. 29.What is 19³? =
  30. 30.What is 5³? =
  31. 31.Which of these is a perfect cube? (a) 552 (b) 512 (c) 631
  32. 32.What is the smallest whole number by which 250 must be multiplied to get a perfect cube?
  33. 33.What is ∛10648? =
  34. 34.What is 6³? =
  35. 35.What is ∛6859? =
  36. 36.A big cube of edge 5 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  37. 37.What is the smallest whole number by which 16 must be divided to get a perfect cube?
  38. 38.What is the smallest whole number by which 32 must be divided to get a perfect cube?
  39. 39.Which of these is a perfect cube? (a) 424 (b) 352 (c) 343
  40. 40.What is ∛15625? =

Answer key

  1. 4
  2. 25
  3. 13
  4. 9
  5. 3375
  6. 8
  7. 9
  8. 10
  9. 9
  10. 343
  11. 49
  12. 27
  13. 17
  14. 21
  15. 16
  16. 6
  17. 4913
  18. 125
  19. 2197
  20. 7
  21. 10
  22. 24
  23. 49
  24. 729
  25. 16
  26. 2
  27. 12
  28. 1331
  29. 6859
  30. 125
  31. 512
  32. 4
  33. 22
  34. 216
  35. 19
  36. 125
  37. 2
  38. 4
  39. 343
  40. 25

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