Is hard-coding literals ever acceptable?

The code base I'm currently working on is littered with hard-coded values. I view all hard coded values as a code smell and I try to eliminate them where possible...however there are some cases that I am unsure about. Here are two examples that I can think of that make me wonder what the best practice is: ``` 1. MyTextBox.Text = someCondition ? "Yes" : "No" 2. double myPercentage = myValue / 100; ``` In the first case, is the best thing to do to create a class that allows me to do MyHelper.Yes and MyHelper.No or perhaps something similar in a config file (though it isn't likely to change and who knows if there might ever be a case where its usage would be case sensitive). In the second case, finding a percentage by dividing by 100 isn't likely to ever change unless the laws of mathematics change...but I still wonder if there is a better way. Can anyone suggest an appropriate way to deal with this sort of hard coding? And can anyone think of any places where hard coding is an acceptable practice?