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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 183 · 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 3 must be multiplied to get a perfect cube?
  2. 2.What is the smallest whole number by which 320 must be divided to get a perfect cube?
  3. 3.What is the smallest whole number by which 432 must be multiplied to get a perfect cube?
  4. 4.What is the smallest whole number by which 448 must be multiplied to get a perfect cube?
  5. 5.What is the smallest whole number by which 81 must be multiplied to get a perfect cube?
  6. 6.A cube has a volume of 64 cubic cm. How long is each edge (in cm)?
  7. 7.A cube has a volume of 1000 cubic cm. How long is each edge (in cm)?
  8. 8.What is 20³? =
  9. 9.What is 12³? =
  10. 10.What is the smallest whole number by which 9 must be divided to get a perfect cube?
  11. 11.A big cube of edge 5 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  12. 12.A cube has a volume of 3375 cubic cm. How long is each edge (in cm)?
  13. 13.A cube has a volume of 343 cubic cm. How long is each edge (in cm)?
  14. 14.Which of these is a perfect cube? (a) 465 (b) 343 (c) 445
  15. 15.Which of these is a perfect cube? (a) 3802 (b) 3375 (c) 3797
  16. 16.What is ∛512? =
  17. 17.Which of these is a perfect cube? (a) 2629 (b) 2197 (c) 2440
  18. 18.A cube has a volume of 6859 cubic cm. How long is each edge (in cm)?
  19. 19.What is ∛4096? =
  20. 20.What is the smallest whole number by which 192 must be multiplied to get a perfect cube?
  21. 21.What is ∛10648? =
  22. 22.What is ∛1000? =
  23. 23.A big cube of edge 8 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  24. 24.What is 8³? =
  25. 25.A big cube of edge 15 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  26. 26.What is ∛12167? =
  27. 27.What is the smallest whole number by which 500 must be multiplied to get a perfect cube?
  28. 28.What is 2³? =
  29. 29.A cube has a volume of 27 cubic cm. How long is each edge (in cm)?
  30. 30.Which of these is a perfect cube? (a) 216 (b) 317 (c) 295
  31. 31.What is the smallest whole number by which 5 must be divided to get a perfect cube?
  32. 32.What is the smallest whole number by which 1080 must be multiplied to get a perfect cube?
  33. 33.A big cube of edge 24 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) 512 (b) 668 (c) 560
  35. 35.A big cube of edge 10 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  36. 36.What is 7³? =
  37. 37.What is the smallest whole number by which 864 must be divided to get a perfect cube?
  38. 38.What is the smallest whole number by which 192 must be divided to get a perfect cube?
  39. 39.Which of these is a perfect cube? (a) 1486 (b) 1331 (c) 1574
  40. 40.Which of these is a perfect cube? (a) 1805 (b) 2120 (c) 1728

Answer key

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

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