convert textbox value from string to either single or double numeric data type

I have a form that takes input from the user. Its a textbox so the value is a string. But the input from the user is actually a real number. Have not decided on the actual data type as yet but i was thinking either single or double data type.

the issue is how to convert this text box string to one of these types.............any ideas?

i know to convert string to
integer i use "Val"
Long i use "Clng"

not sure about single or double data types.

Val works to convert to non-integers.