Versatile and Low Cost Digital Counter

Step 3 Soldering

Now, note there are two sides of the key switch. You'll want to solder a bit of wire on one side of the switch and another length on the other side of the switch.

Now, again, press "+1" and then short the two wires you have just soldered. If all is well, the answer "1" will be displayed.

Reassemble your calculator but be sure to have the wires come out the side of the casing. A quick touch of the soldering iron should melt a nice little pathway or your two wires.