Problem in sorting

Hi,

In my table after sorting my column datas are

1 days
10 days
11 days
3 days
4 days

But i need in the below format after sorting

1 days
3 days
4 days
10 days
11 days

In datatable, if the column data is numeric then its working fine. But if it is a numeric with string its not working. Can you please suggest a solution for this.

Thanks,
Jayaprakash.R