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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 321 · 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 9 must be multiplied to get a perfect cube?
  2. 2.What is the smallest whole number by which 32 must be divided to get a perfect cube?
  3. 3.Which of these is a perfect cube? (a) 138 (b) 125 (c) 127
  4. 4.What is ∛8? =
  5. 5.What is the smallest whole number by which 7 must be divided to get a perfect cube?
  6. 6.A cube has a volume of 2197 cubic cm. How long is each edge (in cm)?
  7. 7.What is 4³? =
  8. 8.Which of these is a perfect cube? (a) 366 (b) 349 (c) 343
  9. 9.A big cube of edge 6 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  10. 10.A cube has a volume of 27 cubic cm. How long is each edge (in cm)?
  11. 11.What is ∛1000? =
  12. 12.What is 16³? =
  13. 13.A big cube of edge 5 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  14. 14.What is 8³? =
  15. 15.A cube has a volume of 8000 cubic cm. How long is each edge (in cm)?
  16. 16.Which of these is a perfect cube? (a) 72 (b) 64 (c) 65
  17. 17.What is 18³? =
  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 9 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  20. 20.What is the smallest whole number by which 1125 must be divided to get a perfect cube?
  21. 21.Which of these is a perfect cube? (a) 1729 (b) 2111 (c) 1728
  22. 22.Which of these is a perfect cube? (a) 3772 (b) 3597 (c) 3375
  23. 23.A cube has a volume of 8 cubic cm. How long is each edge (in cm)?
  24. 24.What is 19³? =
  25. 25.A big cube of edge 12 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  26. 26.What is the smallest whole number by which 392 must be multiplied to get a perfect cube?
  27. 27.What is the smallest whole number by which 250 must be multiplied to get a perfect cube?
  28. 28.A big cube of edge 24 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  29. 29.What is ∛9261? =
  30. 30.What is the smallest whole number by which 320 must be divided to get a perfect cube?
  31. 31.A cube has a volume of 64 cubic cm. How long is each edge (in cm)?
  32. 32.What is 13³? =
  33. 33.What is 11³? =
  34. 34.What is ∛27? =
  35. 35.Which of these is a perfect cube? (a) 245 (b) 253 (c) 216
  36. 36.Which of these is a perfect cube? (a) 47 (b) 50 (c) 27
  37. 37.What is the smallest whole number by which 500 must be multiplied to get a perfect cube?
  38. 38.What is 9³? =
  39. 39.What is ∛8000? =
  40. 40.What is ∛5832? =

Answer key

  1. 3
  2. 4
  3. 125
  4. 2
  5. 7
  6. 13
  7. 64
  8. 343
  9. 216
  10. 3
  11. 10
  12. 4096
  13. 125
  14. 512
  15. 20
  16. 64
  17. 5832
  18. 27
  19. 27
  20. 9
  21. 1728
  22. 3375
  23. 2
  24. 6859
  25. 64
  26. 7
  27. 4
  28. 216
  29. 21
  30. 5
  31. 4
  32. 2197
  33. 1331
  34. 3
  35. 216
  36. 27
  37. 2
  38. 729
  39. 20
  40. 18

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