1) The name "Bluetooth" comes from the 10th-century Danish king, Harald Bluetooth, who united Denmark and Norway.

2) The Federal Reserve System, often referred to as the Fed, is the central banking system of the United States.

3) A single bolt of lightning can heat the surrounding air to temperatures five times hotter than the surface of the sun.

4) The Boston Celtics and the Los Angeles Lakers are the most successful teams in NBA history, with a combined total of 33 championships.