Data field in report builder

Dears

I`v created a data field in sales order which contains a reference number of manual sales order to make it easy to search for a certain sales order in the system

now when i try to print sales order custom report with show total row this data field get sum and the number print out like that

123456789012345678901234567890

so its to hard to get this column printed out into this report the entire design get effected

so is there any idea to exclude this column from show totals function ??

Use float or int instead.