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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 964 · 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) 69 (b) 64 (c) 79
  2. 2.A big cube of edge 2 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  3. 3.Which of these is a perfect cube? (a) 216 (b) 225 (c) 271
  4. 4.What is the smallest whole number by which 9 must be multiplied to get a perfect cube?
  5. 5.What is ∛512? =
  6. 6.Which of these is a perfect cube? (a) 2900 (b) 3083 (c) 2744
  7. 7.A big cube of edge 5 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  8. 8.What is ∛1000? =
  9. 9.What is the smallest whole number by which 10584 must be multiplied to get a perfect cube?
  10. 10.Which of these is a perfect cube? (a) 3375 (b) 3612 (c) 3952
  11. 11.What is ∛4913? =
  12. 12.A cube has a volume of 512 cubic cm. How long is each edge (in cm)?
  13. 13.A cube has a volume of 2744 cubic cm. How long is each edge (in cm)?
  14. 14.A big cube of edge 6 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  15. 15.A cube has a volume of 27 cubic cm. How long is each edge (in cm)?
  16. 16.What is 18³? =
  17. 17.A big cube of edge 18 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  18. 18.What is the smallest whole number by which 864 must be multiplied to get a perfect cube?
  19. 19.A big cube of edge 12 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  20. 20.Which of these is a perfect cube? (a) 1465 (b) 1481 (c) 1331
  21. 21.Which of these is a perfect cube? (a) 131 (b) 141 (c) 125
  22. 22.Which of these is a perfect cube? (a) 2197 (b) 2660 (c) 2546
  23. 23.What is the smallest whole number by which 72 must be multiplied to get a perfect cube?
  24. 24.What is the smallest whole number by which 56 must be multiplied to get a perfect cube?
  25. 25.A cube has a volume of 8 cubic cm. How long is each edge (in cm)?
  26. 26.What is 16³? =
  27. 27.What is the smallest whole number by which 625 must be divided to get a perfect cube?
  28. 28.A big cube of edge 12 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  29. 29.What is 9³? =
  30. 30.What is ∛13824? =
  31. 31.What is ∛6859? =
  32. 32.What is ∛5832? =
  33. 33.A big cube of edge 9 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  34. 34.A big cube of edge 24 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  35. 35.What is the smallest whole number by which 320 must be multiplied to get a perfect cube?
  36. 36.What is 7³? =
  37. 37.A big cube of edge 4 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  38. 38.A cube has a volume of 4096 cubic cm. How long is each edge (in cm)?
  39. 39.What is 12³? =
  40. 40.What is the smallest whole number by which 5 must be multiplied to get a perfect cube?

Answer key

  1. 64
  2. 8
  3. 216
  4. 3
  5. 8
  6. 2744
  7. 125
  8. 10
  9. 7
  10. 3375
  11. 17
  12. 8
  13. 14
  14. 216
  15. 3
  16. 5832
  17. 216
  18. 2
  19. 216
  20. 1331
  21. 125
  22. 2197
  23. 3
  24. 49
  25. 2
  26. 4096
  27. 5
  28. 64
  29. 729
  30. 24
  31. 19
  32. 18
  33. 27
  34. 216
  35. 25
  36. 343
  37. 64
  38. 16
  39. 1728
  40. 25

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