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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 670 · 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 432 must be multiplied to get a perfect cube?
  2. 2.A big cube of edge 3 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  3. 3.What is ∛12167? =
  4. 4.Which of these is a perfect cube? (a) 1220 (b) 1000 (c) 1033
  5. 5.What is ∛3375? =
  6. 6.A big cube of edge 5 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  7. 7.What is ∛1728? =
  8. 8.What is the smallest whole number by which 576 must be multiplied to get a perfect cube?
  9. 9.A cube has a volume of 216 cubic cm. How long is each edge (in cm)?
  10. 10.Which of these is a perfect cube? (a) 1408 (b) 1338 (c) 1331
  11. 11.What is the smallest whole number by which 875 must be multiplied to get a perfect cube?
  12. 12.Which of these is a perfect cube? (a) 216 (b) 263 (c) 243
  13. 13.What is 10³? =
  14. 14.A cube has a volume of 4096 cubic cm. How long is each edge (in cm)?
  15. 15.A cube has a volume of 125 cubic cm. How long is each edge (in cm)?
  16. 16.Which of these is a perfect cube? (a) 644 (b) 512 (c) 693
  17. 17.What is 20³? =
  18. 18.What is the smallest whole number by which 40 must be divided to get a perfect cube?
  19. 19.What is 7³? =
  20. 20.What is ∛10648? =
  21. 21.Which of these is a perfect cube? (a) 2130 (b) 1728 (c) 1944
  22. 22.What is 8³? =
  23. 23.What is 15³? =
  24. 24.What is ∛27? =
  25. 25.What is 19³? =
  26. 26.What is the smallest whole number by which 72 must be multiplied to get a perfect cube?
  27. 27.A big cube of edge 16 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  28. 28.What is the smallest whole number by which 189 must be multiplied to get a perfect cube?
  29. 29.A cube has a volume of 64 cubic cm. How long is each edge (in cm)?
  30. 30.What is the smallest whole number by which 1512 must be divided to get a perfect cube?
  31. 31.What is the smallest whole number by which 135 must be divided to get a perfect cube?
  32. 32.What is the smallest whole number by which 49 must be multiplied to get a perfect cube?
  33. 33.Which of these is a perfect cube? (a) 93 (b) 100 (c) 64
  34. 34.A cube has a volume of 1000 cubic cm. How long is each edge (in cm)?
  35. 35.What is ∛216? =
  36. 36.What is the smallest whole number by which 135 must be multiplied to get a perfect cube?
  37. 37.What is 14³? =
  38. 38.Which of these is a perfect cube? (a) 3871 (b) 3722 (c) 3375
  39. 39.What is 6³? =
  40. 40.A big cube of edge 12 cm is cut into small cubes of edge 3 cm. How many small cubes are there?

Answer key

  1. 4
  2. 27
  3. 23
  4. 1000
  5. 15
  6. 125
  7. 12
  8. 3
  9. 6
  10. 1331
  11. 49
  12. 216
  13. 1000
  14. 16
  15. 5
  16. 512
  17. 8000
  18. 5
  19. 343
  20. 22
  21. 1728
  22. 512
  23. 3375
  24. 3
  25. 6859
  26. 3
  27. 64
  28. 49
  29. 4
  30. 7
  31. 5
  32. 7
  33. 64
  34. 10
  35. 6
  36. 25
  37. 2744
  38. 3375
  39. 216
  40. 64

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