7 is the only real variety D for which the equation 2n − D = x2 has more than two alternatives for n and x purely natural. In particular, the equation 2n − 7 = x2 is known as the Ramanujan–Nagell equation.Jahannam has seven gates that are open up all the time. (Qur’an – Sura fifteen:forty four). Hell also has seven layers and sinners are