//mc2.cpp
 #include <iostream.h>			//cout
 #include <conio.h>				//getch()
 void main()
 { float mass , e , C;
   C = 3e8;						//光速 3x108m/sec
   mass = 50 * 0.1/100;
   e = mass * C * C;				//E=mC2 質能互換公式
   cout << "質量損失=" << e << "焦耳\n";
   getch();
 }