Displaying the sum into a text bokx

[davey]

How can I make a form that when i enter "A" into one text box, and then
"b" into another text box, it will display the total into a third box, and
if i change either a or b it will update it, and then when i go to the next
record it will save it into the table

 

[Van T. Dinh]

Create a TextBox C and set it ControlSource to

= A + b

and DON'T save the value of C into the Table. It is a Calculated Value that
can be re-calculated if you have the value of A & b. It works more
efficiently and avoids inconsistencies buy not storing calculated values.