Put water in a bowl, nuke it in microwave to get hot, put piece of aluminum foil in the water then drop half a table spoon of baking soda in, drop coin in, then drop another half table spoon of baking soda onto it. Let sit for 30 sec-1min, longer if you want then take out of bowl and gently rub with fingers and rinse thoroughly.
Did this to a 40% silver half dollar last week that was totally green with corrosion to the point i couldn't even see the date but could tell it was silver. I left mine in the hot water for 5 mins, and when it came out just touched it up with a little more baking soda in hand, and coin is much cleaner and will go into my silver pile now.