Class 8 Maths Worksheet: Cubes and Cube Roots

Maths worksheets lesson 59: Cubes and cube roots · Set 403 · 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 5³? =
2. 2.What is ∛15625? =
3. 3.What is ∛10648? =
4. 4.What is the smallest whole number by which 500 must be divided to get a perfect cube?
5. 5.What is the smallest whole number by which 243 must be divided to get a perfect cube?
6. 6.A big cube of edge 6 cm is cut into small cubes of edge 1 cm. How many small cubes are there?
7. 7.A big cube of edge 12 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
8. 8.What is the smallest whole number by which 243 must be multiplied to get a perfect cube?
9. 9.A big cube of edge 20 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
10. 10.A big cube of edge 8 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
11. 11.A cube has a volume of 729 cubic cm. How long is each edge (in cm)?
12. 12.What is the smallest whole number by which 200 must be divided to get a perfect cube?
13. 13.What is the smallest whole number by which 448 must be multiplied to get a perfect cube?
14. 14.A cube has a volume of 125 cubic cm. How long is each edge (in cm)?
15. 15.What is the smallest whole number by which 135 must be divided to get a perfect cube?
16. 16.What is 7³? =
17. 17.A big cube of edge 12 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
18. 18.What is 19³? =
19. 19.Which of these is a perfect cube? (a) 27 (b) 31 (c) 39
20. 20.What is ∛729? =
21. 21.What is the smallest whole number by which 864 must be multiplied to get a perfect cube?
22. 22.What is 6³? =
23. 23.A big cube of edge 9 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
24. 24.What is the smallest whole number by which 108 must be divided to get a perfect cube?
25. 25.A big cube of edge 8 cm is cut into small cubes of edge 4 cm. How many small cubes are there?
26. 26.What is 8³? =
27. 27.What is ∛12167? =
28. 28.A big cube of edge 6 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
29. 29.What is the smallest whole number by which 5 must be divided to get a perfect cube?
30. 30.A big cube of edge 15 cm is cut into small cubes of edge 3 cm. How many small cubes are there?
31. 31.What is the smallest whole number by which 128 must be multiplied to get a perfect cube?
32. 32.A big cube of edge 6 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
33. 33.A big cube of edge 10 cm is cut into small cubes of edge 2 cm. How many small cubes are there?
34. 34.What is the smallest whole number by which 81 must be divided to get a perfect cube?
35. 35.A cube has a volume of 8 cubic cm. How long is each edge (in cm)?
36. 36.What is the smallest whole number by which 16 must be multiplied to get a perfect cube?
37. 37.What is 14³? =
38. 38.What is ∛6859? =
39. 39.What is the smallest whole number by which 1080 must be multiplied to get a perfect cube?
40. 40.A cube has a volume of 2197 cubic cm. How long is each edge (in cm)?

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