It is famous as a bluffing power in the 5th edition of the D&D role-playing game. This skill is used for bluffing and deception to some characters. To calculate your skill score you just have to add the relevant proficient score to the proficient score of your character. If you're facing any doubt then you can clear it with the help of a character sheet booklet. Suppose your relevant proficient score is +2 and your proficient score is +2 then your skill score becomes +4.