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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 8 · 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 7 must be multiplied to get a perfect cube?
  2. 2.Which of these is a perfect cube? (a) 797 (b) 729 (c) 806
  3. 3.What is the smallest whole number by which 875 must be multiplied to get a perfect cube?
  4. 4.What is the smallest whole number by which 16 must be multiplied to get a perfect cube?
  5. 5.What is 18³? =
  6. 6.A cube has a volume of 216 cubic cm. How long is each edge (in cm)?
  7. 7.What is ∛27? =
  8. 8.What is ∛4096? =
  9. 9.Which of these is a perfect cube? (a) 1534 (b) 1331 (c) 1545
  10. 10.Which of these is a perfect cube? (a) 1280 (b) 1246 (c) 1000
  11. 11.What is the smallest whole number by which 128 must be multiplied to get a perfect cube?
  12. 12.What is ∛4913? =
  13. 13.A big cube of edge 4 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  14. 14.A cube has a volume of 8 cubic cm. How long is each edge (in cm)?
  15. 15.What is 17³? =
  16. 16.Which of these is a perfect cube? (a) 1787 (b) 2073 (c) 1728
  17. 17.A cube has a volume of 3375 cubic cm. How long is each edge (in cm)?
  18. 18.A cube has a volume of 2197 cubic cm. How long is each edge (in cm)?
  19. 19.What is 19³? =
  20. 20.What is ∛8000? =
  21. 21.What is the smallest whole number by which 1600 must be divided to get a perfect cube?
  22. 22.What is the smallest whole number by which 54 must be divided to get a perfect cube?
  23. 23.A big cube of edge 15 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  24. 24.What is the smallest whole number by which 2 must be divided to get a perfect cube?
  25. 25.A cube has a volume of 1000 cubic cm. How long is each edge (in cm)?
  26. 26.A cube has a volume of 1331 cubic cm. How long is each edge (in cm)?
  27. 27.A big cube of edge 8 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  28. 28.Which of these is a perfect cube? (a) 583 (b) 512 (c) 689
  29. 29.What is ∛125? =
  30. 30.A big cube of edge 5 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  31. 31.Which of these is a perfect cube? (a) 41 (b) 31 (c) 27
  32. 32.What is the smallest whole number by which 3136 must be multiplied to get a perfect cube?
  33. 33.What is ∛15625? =
  34. 34.A big cube of edge 2 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  35. 35.A big cube of edge 6 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  36. 36.Which of these is a perfect cube? (a) 64 (b) 109 (c) 74
  37. 37.What is the smallest whole number by which 135 must be multiplied to get a perfect cube?
  38. 38.Which of these is a perfect cube? (a) 193 (b) 125 (c) 165
  39. 39.What is the smallest whole number by which 32 must be multiplied to get a perfect cube?
  40. 40.What is 10³? =

Answer key

  1. 49
  2. 729
  3. 49
  4. 4
  5. 5832
  6. 6
  7. 3
  8. 16
  9. 1331
  10. 1000
  11. 4
  12. 17
  13. 8
  14. 2
  15. 4913
  16. 1728
  17. 15
  18. 13
  19. 6859
  20. 20
  21. 25
  22. 2
  23. 125
  24. 2
  25. 10
  26. 11
  27. 64
  28. 512
  29. 5
  30. 125
  31. 27
  32. 7
  33. 25
  34. 8
  35. 8
  36. 64
  37. 25
  38. 125
  39. 2
  40. 1000

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