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 Eiffel Tower can be 15 cm taller during the summer due to thermal expansion.

4) In Hindu mythology, the Bhagavad Gita is a sacred text that contains a conversation between Prince Arjuna and the god Krishna, who serves as his charioteer. It delves into philosophical and moral dilemmas and provides guidance on duty, righteousness, and the path to spiritual enlightenment.