iBacknine is an iPhone/Apple Watch application for serious golfers who play very hard to earn a few dollars against opponents.

It allows you to record everybody's scores with a few taps (either on Apple Watch or iPhone) between holes, and see the summary of scores, and individual matches (Nassau games between each players) at the turn or at the end of round.

iBacknine works fine with an iPhone alone, but it works extremely well with Apple Watch. It allows you to focus on the golf game itself instead of fiddling with numbers.