* Radha Gobinda Chandra, a Bangladeshi-Indian astronomer recorded more than 49,700 new stars. * * Bluetooth is named after a Danish King. * Chicken odour repels mosquitoes. * Unreadable handwriting is called griffonage. * There are four new additions to the Periodic Table. * A waterfall in Hawaii sometimes goes up instead of down. Did You Know 4? includes and explains several interesting facts around us that normally go unnoticed but have a bearing on our day-to-day life. This volume will amaze the readers with its wide coverage of topics and excite them with the unexpected.