This app was mentioned in 1 comment, with an average of 1.00 upvote
https://play.google.com/store/apps/details?id=com.ksphr.ygolifecalculator
Easily my favorite one. No frills, no gaudy design, no diving into menus or unintuitive button combinations.
Also a good one if you have Internet access, has ready access to rulings and keeps a log of events.