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

2) The strongest natural material known to man is spider silk. It is stronger than steel and more flexible than nylon.

3) The first commercially successful video game was "Pong," released in 1972 by Atari.

4) The abolition of slavery in the United States was officially proclaimed with the ratification of the 13th Amendment to the Constitution in 1865.