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Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 66 · 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 16 must be multiplied to get a perfect cube?
  2. 2.What is ∛729? =
  3. 3.What is 11³? =
  4. 4.What is the smallest whole number by which 81 must be multiplied to get a perfect cube?
  5. 5.A cube has a volume of 27 cubic cm. How long is each edge (in cm)?
  6. 6.A cube has a volume of 729 cubic cm. How long is each edge (in cm)?
  7. 7.Which of these is a perfect cube? (a) 97 (b) 64 (c) 112
  8. 8.What is 16³? =
  9. 9.Which of these is a perfect cube? (a) 225 (b) 254 (c) 216
  10. 10.What is the smallest whole number by which 625 must be multiplied to get a perfect cube?
  11. 11.What is ∛216? =
  12. 12.What is the smallest whole number by which 1600 must be divided to get a perfect cube?
  13. 13.Which of these is a perfect cube? (a) 40 (b) 45 (c) 27
  14. 14.A cube has a volume of 4096 cubic cm. How long is each edge (in cm)?
  15. 15.What is 9³? =
  16. 16.Which of these is a perfect cube? (a) 2376 (b) 2197 (c) 2345
  17. 17.What is ∛125? =
  18. 18.A cube has a volume of 6859 cubic cm. How long is each edge (in cm)?
  19. 19.What is ∛4913? =
  20. 20.What is 3³? =
  21. 21.A cube has a volume of 216 cubic cm. How long is each edge (in cm)?
  22. 22.What is ∛8000? =
  23. 23.A big cube of edge 10 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
  24. 24.What is ∛512? =
  25. 25.Which of these is a perfect cube? (a) 1331 (b) 1357 (c) 1609
  26. 26.What is the smallest whole number by which 128 must be multiplied to get a perfect cube?
  27. 27.Which of these is a perfect cube? (a) 1208 (b) 1003 (c) 1000
  28. 28.A big cube of edge 12 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  29. 29.What is the smallest whole number by which 1944 must be multiplied to get a perfect cube?
  30. 30.A big cube of edge 4 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
  31. 31.What is the smallest whole number by which 243 must be divided to get a perfect cube?
  32. 32.What is the smallest whole number by which 135 must be multiplied to get a perfect cube?
  33. 33.A big cube of edge 24 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
  34. 34.What is the smallest whole number by which 189 must be divided to get a perfect cube?
  35. 35.What is the smallest whole number by which 648 must be multiplied to get a perfect cube?
  36. 36.What is the smallest whole number by which 2 must be divided to get a perfect cube?
  37. 37.Which of these is a perfect cube? (a) 2153 (b) 1953 (c) 1728
  38. 38.What is 7³? =
  39. 39.What is 4³? =
  40. 40.What is ∛8? =

Answer key

  1. 4
  2. 9
  3. 1331
  4. 9
  5. 3
  6. 9
  7. 64
  8. 4096
  9. 216
  10. 25
  11. 6
  12. 25
  13. 27
  14. 16
  15. 729
  16. 2197
  17. 5
  18. 19
  19. 17
  20. 27
  21. 6
  22. 20
  23. 125
  24. 8
  25. 1331
  26. 4
  27. 1000
  28. 27
  29. 3
  30. 64
  31. 9
  32. 25
  33. 216
  34. 7
  35. 9
  36. 2
  37. 1728
  38. 343
  39. 64
  40. 2

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