1) The concept of compound interest can be attributed to the ancient Babylonians, who used it in their banking practices.

2) The concept of proportional representation, used in some electoral systems, aims to ensure that political parties' representation in government aligns more closely with the proportion of votes they receive from the electorate.

3) The most-watched TV series finale in the United States was "MAS*H," with an estimated 105 million viewers.

4) The word "mountain" contains three vowels: O, U, and A.