Here is a calculator for them that I have created. http://www.gxseries.com/numis/asian_yr/asian_yr.htm They are both Japanese by the way.
Your first coin is a 1 yen coin in aluminum. The year is Showa era 46, or 1971AD. In Japan the year is counted as the reign year of the reigning emperor. So, the Showa era began on the ascession on the throne of emperor Hirohito.The Showa era started in 1926 and ended in 1989. The era of emperor Akihito, who is now the Japanese emperor, is called the Heisei era, starting in 1989. The other coin is a 50 yen of Showa year 45 or 1970AD.
Okay, I'm confused. The bottom legend is "Sho Wa Go Ju Ichi Nen", which I would translate as "Showa 56" (1981). What am I missing?
You're right, hontonai! It says 56 (5-10-6). I got confused with th other coin (45) and typed wrongly 46 instead of 56.