mass–energy equivalence states that anything having mass has an equivalent amount of energy and vice versa
This formula states that the equivalent energy (E) can be calculated as the mass (m) multiplied by the speed of light squared. Similarly, anything having energy exhibits a corresponding mass m given by its energy E divided by the speed of light squared c². Because the speed of light is a very large number in everyday units, the formula implies that even an everyday object at rest with a modest amount of mass has a very large amount of energy intrinsically.