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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 658 · 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) 295 (b) 221 (c) 216
  2. 2.Which of these is a perfect cube? (a) 64 (b) 102 (c) 65
  3. 3.What is the smallest whole number by which 1512 must be divided to get a perfect cube?
  4. 4.What is ∛216? =
  5. 5.What is 16³? =
  6. 6.What is 7³? =
  7. 7.A big cube of edge 4 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  8. 8.What is ∛4096? =
  9. 9.What is ∛1331? =
  10. 10.What is ∛15625? =
  11. 11.What is the smallest whole number by which 576 must be divided to get a perfect cube?
  12. 12.A big cube of edge 6 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  13. 13.A big cube of edge 8 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  14. 14.What is ∛8000? =
  15. 15.A big cube of edge 24 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  16. 16.A big cube of edge 18 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  17. 17.A big cube of edge 5 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  18. 18.What is ∛3375? =
  19. 19.Which of these is a perfect cube? (a) 2077 (b) 1728 (c) 1825
  20. 20.What is 19³? =
  21. 21.What is ∛4913? =
  22. 22.A big cube of edge 12 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  23. 23.What is 11³? =
  24. 24.What is ∛8? =
  25. 25.What is the smallest whole number by which 7 must be multiplied to get a perfect cube?
  26. 26.Which of these is a perfect cube? (a) 1331 (b) 1454 (c) 1611
  27. 27.A cube has a volume of 2744 cubic cm. How long is each edge (in cm)?
  28. 28.A big cube of edge 12 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  29. 29.What is ∛1000? =
  30. 30.What is the smallest whole number by which 40 must be multiplied to get a perfect cube?
  31. 31.What is ∛2197? =
  32. 32.A cube has a volume of 8 cubic cm. How long is each edge (in cm)?
  33. 33.What is the smallest whole number by which 25 must be divided to get a perfect cube?
  34. 34.What is 12³? =
  35. 35.Which of these is a perfect cube? (a) 28 (b) 27 (c) 46
  36. 36.What is 8³? =
  37. 37.What is 9³? =
  38. 38.A cube has a volume of 4096 cubic cm. How long is each edge (in cm)?
  39. 39.What is 20³? =
  40. 40.What is 3³? =

Answer key

  1. 216
  2. 64
  3. 7
  4. 6
  5. 4096
  6. 343
  7. 8
  8. 16
  9. 11
  10. 25
  11. 9
  12. 216
  13. 8
  14. 20
  15. 216
  16. 216
  17. 125
  18. 15
  19. 1728
  20. 6859
  21. 17
  22. 64
  23. 1331
  24. 2
  25. 49
  26. 1331
  27. 14
  28. 216
  29. 10
  30. 25
  31. 13
  32. 2
  33. 25
  34. 1728
  35. 27
  36. 512
  37. 729
  38. 16
  39. 8000
  40. 27

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