Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 780 · 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.What is the smallest whole number by which 5400 must be multiplied to get a perfect cube?
2. 2.Which of these is a perfect cube? (a) 2197 (b) 2674 (c) 2240
3. 3.What is the smallest whole number by which 500 must be multiplied to get a perfect cube?
4. 4.What is the smallest whole number by which 49 must be divided to get a perfect cube?
5. 5.What is the smallest whole number by which 4 must be divided to get a perfect cube?
6. 6.What is ∛8000? =
7. 7.What is ∛125? =
8. 8.Which of these is a perfect cube? (a) 125 (b) 157 (c) 137
9. 9.Which of these is a perfect cube? (a) 68 (b) 64 (c) 96
10. 10.A cube has a volume of 6859 cubic cm. How long is each edge (in cm)?
11. 11.What is 5³? =
12. 12.What is 7³? =
13. 13.What is the smallest whole number by which 5 must be divided to get a perfect cube?
14. 14.Which of these is a perfect cube? (a) 1728 (b) 2063 (c) 1731
15. 15.What is ∛3375? =
16. 16.A big cube of edge 12 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
17. 17.A big cube of edge 8 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
18. 18.What is ∛729? =
19. 19.What is 4³? =
20. 20.Which of these is a perfect cube? (a) 27 (b) 33 (c) 54
21. 21.What is ∛2744? =
22. 22.What is ∛12167? =
23. 23.Which of these is a perfect cube? (a) 2941 (b) 3139 (c) 2744
24. 24.What is ∛10648? =
25. 25.What is the smallest whole number by which 49 must be multiplied to get a perfect cube?
26. 26.What is 16³? =
27. 27.What is 9³? =
28. 28.What is the smallest whole number by which 81 must be multiplied to get a perfect cube?
29. 29.A big cube of edge 20 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
30. 30.Which of these is a perfect cube? (a) 216 (b) 254 (c) 261
31. 31.What is 15³? =
32. 32.What is ∛4913? =
33. 33.A big cube of edge 6 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
34. 34.A big cube of edge 15 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
35. 35.What is the smallest whole number by which 81 must be divided to get a perfect cube?
36. 36.What is 6³? =
37. 37.What is the smallest whole number by which 2 must be divided to get a perfect cube?
38. 38.What is 2³? =
39. 39.What is 11³? =
40. 40.A big cube of edge 4 cm is cut into small cubes of edge 1 cm. How many small cubes are there?

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