Question:
I try to make a point of being one of the first 10 people in shul. Sometimes, before shmone esrei I need to leave the shul to use the facilities (there will remain a minyan in the shul without me). Do I lose the schar of the being the one of the first 10?
Answer:
If you are davening shemon esrei with the minyan you will not lose the sechar of asara rishonim, but if you don't daven with them, then you would.
Sources:
Sulchan Aruch O:Ch 90-14, M:B ibid 47.
