Reverse Polish notation is one method of expressing calculations.

Polish notation is one of the methods to express arithmetic expressions.

It's difficult to solve this formula.

My grandparents came from Poland.

His poetry depicts emotions with beautiful expressions.

He ate one apple.

Please tell me the way to solve this problem.

My friend came from Poland.

This is the first time I've seen this notation.

He is not good at expressing his feelings in words.