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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 574 · 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.Which of these is a perfect cube? (a) 237 (b) 216 (c) 291
  2. 2.Which of these is a perfect cube? (a) 138 (b) 200 (c) 125
  3. 3.What is 5³? =
  4. 4.Which of these is a perfect cube? (a) 88 (b) 64 (c) 100
  5. 5.What is the smallest whole number by which 7 must be multiplied to get a perfect cube?
  6. 6.Which of these is a perfect cube? (a) 42 (b) 51 (c) 27
  7. 7.What is ∛15625? =
  8. 8.What is 20³? =
  9. 9.What is the smallest whole number by which 2 must be multiplied to get a perfect cube?
  10. 10.Which of these is a perfect cube? (a) 2744 (b) 3010 (c) 3268
  11. 11.What is the smallest whole number by which 32 must be divided to get a perfect cube?
  12. 12.A big cube of edge 12 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  13. 13.What is the smallest whole number by which 49 must be multiplied to get a perfect cube?
  14. 14.What is the smallest whole number by which 648 must be multiplied to get a perfect cube?
  15. 15.What is 11³? =
  16. 16.Which of these is a perfect cube? (a) 2052 (b) 2134 (c) 1728
  17. 17.What is ∛512? =
  18. 18.What is 7³? =
  19. 19.What is ∛343? =
  20. 20.What is ∛10648? =
  21. 21.A cube has a volume of 1000 cubic cm. How long is each edge (in cm)?
  22. 22.What is 15³? =
  23. 23.What is the smallest whole number by which 432 must be multiplied to get a perfect cube?
  24. 24.What is 6³? =
  25. 25.What is the smallest whole number by which 1600 must be divided to get a perfect cube?
  26. 26.What is ∛729? =
  27. 27.What is the smallest whole number by which 2 must be divided to get a perfect cube?
  28. 28.A big cube of edge 8 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  29. 29.What is the smallest whole number by which 1512 must be divided to get a perfect cube?
  30. 30.What is the smallest whole number by which 1125 must be multiplied to get a perfect cube?
  31. 31.What is the smallest whole number by which 4 must be multiplied to get a perfect cube?
  32. 32.What is 8³? =
  33. 33.What is the smallest whole number by which 128 must be divided to get a perfect cube?
  34. 34.What is 13³? =
  35. 35.What is ∛8000? =
  36. 36.A cube has a volume of 2744 cubic cm. How long is each edge (in cm)?
  37. 37.What is ∛216? =
  38. 38.What is the smallest whole number by which 192 must be divided to get a perfect cube?
  39. 39.What is 12³? =
  40. 40.A big cube of edge 2 cm is cut into small cubes of edge 1 cm. How many small cubes are there?

Answer key

  1. 216
  2. 125
  3. 125
  4. 64
  5. 49
  6. 27
  7. 25
  8. 8000
  9. 4
  10. 2744
  11. 4
  12. 64
  13. 7
  14. 9
  15. 1331
  16. 1728
  17. 8
  18. 343
  19. 7
  20. 22
  21. 10
  22. 3375
  23. 4
  24. 216
  25. 25
  26. 9
  27. 2
  28. 64
  29. 7
  30. 3
  31. 2
  32. 512
  33. 2
  34. 2197
  35. 20
  36. 14
  37. 6
  38. 3
  39. 1728
  40. 8

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