Converting Submited String

i got some text fields im submitting by a form and i need to add the field to the current field in the table but the field is text in the table so when i do this

request.form("dkp1") + getraids.fields.item("dkp1").value

i have dkp1 = 10 from the form
and 20 in getraids field

and the above calculation it dosn add but puts them to getter as a string like 1020 and i need to calculate it to 30. my real question is there a way u can define the request.form(dkp1) to be converted from text to numberic ? and getraids of course or do i realy need to change the field type in the table ?