A number which is equal to the sum of its divisors except itself:
In organ transplantation, the transplantation of cornea is easy but other are more complicated. So the principle of histocompalibility should be applied. In this process, the most significant drawback is that the body in which organ is transplanted do not accept it because it recognizes non-self organ and therefore, its immune system is triggered. Body wants to reject the non-self organ.
In the universe, there are different types of force but I am going to explain about these forces which created in the origin of the universe. These forces are strong force, weak force, electromagnetic force and gravitational force. In the time of big bang, these four fundamental forces were believed as a single force, called unified force.
When we throw any object into sky, then it returns back to earth’s surface. Rivers and streams flow downward from hills and mountains. Rainfall occurs in the downward direction. Earth revolves around sun and moon revolves around earth. Eight planets of solar system moves around the sun. Atmosphere surrounds the earth.
