This project is trivial. You take an ATTiny25/45/85 (your choice based on whatever's handy) and you fuse it for an external clock input (so set the LFUSE to 0xe0). Upload the code. Apply the 10 MHz input to pin 2 and you'll get a 1 Hz output on pin 6. Pin 4 is ground, pin 7 is Vcc and pins 3 and 5 are not connected.

What highlights this project is that the code compiles into 452 bytes of text and 4 bytes of data, which makes it enterable into the Hackaday 1K contest.