Power dissipation across resistors in series

Suppose we have a simple circuit with an input voltage source $V$ and two resistors.

Now if we want to find the power dissipated by each resistor using the formula $V^2/R$, should the voltage be the input voltage or the voltage across that specific resistor.

I have this question because, in a series connection, voltage across different components is different.

• Adding a simple procedure to go with RedGrittyBrick's answer: First, find the total resistance. That's easy, just add 'em up. Then find the current. That's easy too: Ohm's Law. Now calculate the power dissipated in each resistor as $I^2R$. – Solomon Slow Apr 6 '15 at 16:14