Build digital counting and frequency-divider circuits with the 74LS90 Decade Counter IC. This 14-pin logic chip can be configured to count from 0 to 9 with binary-coded decimal (BCD) outputs. Separate divide-by-2 and divide-by-5 sections provide flexible counting options, while reset-to-zero and set-to-nine inputs simplify circuit control. Operating from a 5V supply (4.75–5.25V), it is a practical choice for pulse counters, digital clock circuits, educational experiments, and DIY electronics projects.