This app was mentioned in 3 comments, with an average of 1.00 upvote
The Currency Converter app will give the exchange rate:https://play.google.com/store/apps/details?id=sk.halmi.ccalc Currently $1.00 Singapore is $0.73 US, & $1.00 US is $1.36 Singapore, according to this app.
For currency conversion on Android I use: https://play.google.com/store/apps/details?id=sk.halmi.ccalc
Maybe have a look at this one https://play.google.com/store/apps/details?id=sk.halmi.ccalc