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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 17 · 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 ∛8000? =
  2. 2.Which of these is a perfect cube? (a) 216 (b) 287 (c) 278
  3. 3.A big cube of edge 6 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  4. 4.What is 15³? =
  5. 5.Which of these is a perfect cube? (a) 1827 (b) 1728 (c) 1747
  6. 6.What is ∛1728? =
  7. 7.What is 6³? =
  8. 8.A cube has a volume of 64 cubic cm. How long is each edge (in cm)?
  9. 9.What is 3³? =
  10. 10.What is the smallest whole number by which 243 must be divided to get a perfect cube?
  11. 11.What is 14³? =
  12. 12.What is 7³? =
  13. 13.A cube has a volume of 8 cubic cm. How long is each edge (in cm)?
  14. 14.A cube has a volume of 8000 cubic cm. How long is each edge (in cm)?
  15. 15.A cube has a volume of 4096 cubic cm. How long is each edge (in cm)?
  16. 16.Which of these is a perfect cube? (a) 3048 (b) 2955 (c) 2744
  17. 17.Which of these is a perfect cube? (a) 27 (b) 37 (c) 47
  18. 18.What is the smallest whole number by which 320 must be divided to get a perfect cube?
  19. 19.What is 12³? =
  20. 20.Which of these is a perfect cube? (a) 1444 (b) 1331 (c) 1457
  21. 21.Which of these is a perfect cube? (a) 1000 (b) 1246 (c) 1082
  22. 22.What is the smallest whole number by which 81 must be multiplied to get a perfect cube?
  23. 23.What is 10³? =
  24. 24.Which of these is a perfect cube? (a) 135 (b) 125 (c) 157
  25. 25.What is the smallest whole number by which 32 must be multiplied to get a perfect cube?
  26. 26.Which of these is a perfect cube? (a) 473 (b) 343 (c) 409
  27. 27.A cube has a volume of 3375 cubic cm. How long is each edge (in cm)?
  28. 28.What is 20³? =
  29. 29.What is the smallest whole number by which 108 must be divided to get a perfect cube?
  30. 30.What is 5³? =
  31. 31.What is the smallest whole number by which 3136 must be multiplied to get a perfect cube?
  32. 32.What is ∛8? =
  33. 33.What is 2³? =
  34. 34.Which of these is a perfect cube? (a) 71 (b) 64 (c) 97
  35. 35.Which of these is a perfect cube? (a) 2197 (b) 2316 (c) 2338
  36. 36.What is the smallest whole number by which 3 must be multiplied to get a perfect cube?
  37. 37.What is 19³? =
  38. 38.What is ∛729? =
  39. 39.A big cube of edge 9 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
  40. 40.What is ∛4096? =

Answer key

  1. 20
  2. 216
  3. 8
  4. 3375
  5. 1728
  6. 12
  7. 216
  8. 4
  9. 27
  10. 9
  11. 2744
  12. 343
  13. 2
  14. 20
  15. 16
  16. 2744
  17. 27
  18. 5
  19. 1728
  20. 1331
  21. 1000
  22. 9
  23. 1000
  24. 125
  25. 2
  26. 343
  27. 15
  28. 8000
  29. 4
  30. 125
  31. 7
  32. 2
  33. 8
  34. 64
  35. 2197
  36. 9
  37. 6859
  38. 9
  39. 27
  40. 16

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