Math app replacing values in text attribute instead adding digits
Im trying to make a math app that displays a problem and then you type in the solution using only numbers on a calculator like number pad. The issue im having is that the numbers are not being saved in the text attribute when i hit multiple number pad buttons. when i click on "1" then "2" im getting a "1" on the display then it replaces the one with a "2". but i want a "12".
im sure there is a simple solution to this, its just alluding me right now.
any help would be great