1. If I am not sure about the dates of employment and residence, can I just put month and year or do I need to estimate? If estimate, how should I let them know those are estimates? 2. If I had a different name a long time ago, but it is not mentioned anywhere in the United States, do I need to mention it on N400? I was born in Armenia, and had my father's last name. Then my mother changed it to hers. Later, I moved to Russia, and my mother's husband officially adopted me, so my last name changed again, after which I received both Armenian passport and Russian citizenship with that last name. So, my other last names were only mentioned on my old birth certificates and nowhere else. And my green card has the same last name as in those passports. So, do I mention it on N400?