Addition Of one static textbox and two usercontrol textboxes columwise

i am taking one row with 15 text boxes in asp.net page ,and second row i am taking user control (.ascx) page with same number of text boxes,similarly third row taking same .ascx page with 15 textboxes,i want to addition of these text box values in column wise like if i am taking first row first text box value and second row first textbox value and third row first textbox value , i want to know addition of all first textboxs values into another textbox called total,lly second textbox,third,fourth columnwise