Yes dopii here's an example of E=mc2
For instance, in one kilogram of pure water, the mass of hydrogen atoms amounts to just slightly more than 111 grams, or 0.111 kg.
Einstein's formula tells us the amount of energy this mass would be equivalent to, if it were all suddenly turned into energy. It says that to find the energy, you multiply the mass by the square of the speed of light, this number being 300,000,000 meters per second (a very large number):
E=mc2
= 0.111 x 300,000,000 x 300,000,000
= 10,000,000,000,000,000 Joules