Please see the eform tag in the form template chunk, rg. eform="Name:string:1" ... make the last "1", "0" and you are good.
For detailed information please consult eform docs.

<label accesskey="n" for="name" class="lbleForm">Name</label><input type="text" name="name" maxlength="60" eform="Your Name::0:Expected at least two words:#REGEX /^\w+\s\w+/i" /><br /><br />
[!eForm? &formid=`feedbackForm` &to=`[email protected]` &tpl=`eFeedBackForm` &report=`eFeedbackReport` &thankyou=`eFeedbackThanks` &vericode=`1` &subject=`Open Writer`!]

<label accesskey="s" for="phone" class="lbleForm">Phone</label><input name="phone" type="text" eform="Your Phone:integer:1::" /><br /><br />


Give Float a try.
