Well, my first bit of advice would be to fix the CSV import so that the data comes in using the correct format. This will save you further work down the line and would be the best method.
To convert any text to a numeric you use the input function:
new_variable = input(<text string>,<informat>);
<text string> can be any valid text string or a character variable.
<informat> can be any valid SAS provided or user defined informat.
These links will help.
http://support.sas.com/publishing/pubcat/chaps/59498.pdf
http://support.sas.com/documentation/cdl/en/lrdict/64316/HTML/default/viewer.htm#a001263753.htm
And yes, to do any form of numeric function, then the item in question should be numeric.
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