SUM() fn is forcing exponential notation on the result in etext template regardless of formatting sp

this is a payment etext template used to generate electronic payments to the bank. The bank has a requirement of a specific algorithm to calculate a hash total on the sum of the recipient account numbers:

1) take the first 15 characters of the account number (i am usign substring for this - no problem here)

2) any non-numeric embedded character must be replaced with a 1  (i am using a series of replace statements for this - again, no problem)

3) ignore any trailing blanks, do not convert them - no problem here

4) sum the account numbers produced by steps 1,2,3 - here is the problem. The sum function is always producing an output in expenonential notation, I.E. 1.234111573421E12   I cannot get this to format back to its proper format.