validate dynamically created textbox to enter only numbers

validate dynamically created textbox to enter only numbers

I have created textbox dynamically which goes on adding on button click
which is working fine, but now I want to validate that each textbox which
is dynamically created should take only numerical data as input. how can I
do that. I have not used jquery to create textbox dynamically but used C#
in asp.net.
I am new to this I have no Idea, Please help me doing this as it is urgent.