Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 798 · 40 sums

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.

1. 1.A big cube of edge 6 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
2. 2.What is 2³? =
3. 3.What is the smallest whole number by which 6125 must be divided to get a perfect cube?
4. 4.A big cube of edge 5 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
5. 5.A cube has a volume of 3375 cubic cm. How long is each edge (in cm)?
6. 6.What is the smallest whole number by which 1080 must be divided to get a perfect cube?
7. 7.What is ∛8? =
8. 8.A big cube of edge 6 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
9. 9.What is the smallest whole number by which 375 must be divided to get a perfect cube?
10. 10.Which of these is a perfect cube? (a) 131 (b) 181 (c) 125
11. 11.A big cube of edge 12 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
12. 12.A big cube of edge 9 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
13. 13.Which of these is a perfect cube? (a) 1045 (b) 1000 (c) 1228
14. 14.What is the smallest whole number by which 40 must be multiplied to get a perfect cube?
15. 15.What is 5³? =
16. 16.What is 15³? =
17. 17.What is 8³? =
18. 18.What is ∛8000? =
19. 19.Which of these is a perfect cube? (a) 2375 (b) 2282 (c) 2197
20. 20.What is ∛13824? =
21. 21.What is 13³? =
22. 22.What is ∛2197? =
23. 23.What is ∛4913? =
24. 24.Which of these is a perfect cube? (a) 1502 (b) 1331 (c) 1485
25. 25.A cube has a volume of 4096 cubic cm. How long is each edge (in cm)?
26. 26.What is the smallest whole number by which 54 must be multiplied to get a perfect cube?
27. 27.What is 4³? =
28. 28.What is ∛6859? =
29. 29.What is ∛5832? =
30. 30.What is ∛64? =
31. 31.What is the smallest whole number by which 56 must be multiplied to get a perfect cube?
32. 32.What is ∛1000? =
33. 33.What is 14³? =
34. 34.What is ∛10648? =
35. 35.A cube has a volume of 64 cubic cm. How long is each edge (in cm)?
36. 36.Which of these is a perfect cube? (a) 3683 (b) 3965 (c) 3375
37. 37.What is the smallest whole number by which 24 must be divided to get a perfect cube?
38. 38.Which of these is a perfect cube? (a) 254 (b) 281 (c) 216
39. 39.What is the smallest whole number by which 3 must be multiplied to get a perfect cube?
40. 40.What is 12³? =

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