Counting the number of entities in a location or passing by is considered a rudimentary skill. However, once you get past a certain amount of items (for example people or animals) in an area, add in an occasional distraction and all of a sudden you may start to wonder if you were at a value of X, or was it X-1, or perhaps even Y or Z.
To avert these numerical inaccuracies, and allow you to practice your surface mount and through-hole soldering skills – you might consider the Digital Tally Counter by Making Devices. The counter features a 4-digit, 7-segment display panel counts up to 9999, and a set of green and red buttons that increment and decrement the count respectively.
As shown in the video below, the buzzer optionally beeps when the count is changed, and a long press on the red button resets the count to zero. After 60 seconds, the device goes to sleep to save power, keeping the numerical value stored.
A PIC18LF14K50 low power microcontroller runs the device, allowing it to draw ~50 nanoamps when asleep, virtually negligible unless you plan to pick it up in a few hundred years. Active usage will get you in the 30-35 hour range, plenty of time accurately keeping track of… anything! The device can be ordered as a kit with only the µC soldered on, or fully assembled if you just need to get counting!
More info on the device can be found on this Hackaday.io post.