This is the 6737th most frequent Japanese word.
パー
"パー" (Pā) can mean "fool" or "idiot" in slang, or refer to the hand gesture "paper" in the game rock-paper-scissors.
In this sentence, 'パー' is used idiomatically to mean 'worthless' or 'a failure.'
彼の算数の答えは全てパーになった。
His answers in arithmetic all turned out wrong.
Here, 'パー' is used as slang to describe 'clear' or 'pure,' usually in relation to air or atmosphere.
この部屋の空気は完全にパーだ。
The air in this room feels very fresh.
In this context, 'パー' refers to the informal shortening of the English word 'full power,' indicating maximum level.