Decaplexing

There are many ways to multiplex LED’s. Some don’t use external circuits some do, however they either take a lot of pins or require custom LED layout. Decaplexing would require one IC, one capacitor and three resistors. It would also allow a four character seven segment to use 5 I/O pins. Decade counters are easy to find online for 79 cents

Step 1 Building the Circuit

It looks a little confusing at first but its really not. The PIC12F629 is the most basic microcontroller I know of and is in this circuit to demonstrate the multiplexing ability.
It is not critical which decade output the segments are on, the Q's can go to the closest segment pin. (I like Q0 to go to G so its dual line at start up) The most important part is the two resistors and cap in the middle, they make an auto reset so the decade starts at Q0 at startup. I've included a labeled segment display.