OK here we go;) The real Equation not the "simplified" version;
E = m * gamma * c^2
When v = 0, it is just E = m * c^2, which is called the rest mass energy because the object is at resting state
(v = 0).
However, if v is small in comparison to that of c, then E - m*c^2 = 1/2 * m * v^2. The energy minus the rest mass energy is equal to the old familiar kinetic energy. In the approximation that v/c << 1.
Standard Theory of Relativity <--didn't know there was such a monster did you;)
Taylor Series approximation states:
1/Sqrt(1+v^2/c^2) ~ 1 + 1/2 * v^2/c^2 if v/c << 1
Again math is a tool, not a full reality.
Get What I am saying?
Don't think it's true..do some research..You will see that that is the Real Equation..