Mass of Pion in Gev/c^2: Calculate and Convert

[Abby D]

The mass of a pion is 2.5x10^-28kg.
Calculate the mass of a pion in Gev/c^2.


I really don't understand how to do these, as I always divide/multiply the wrong numbers etc.
Does anyone have any ways to remember which way round you do it? (1eV = 1.6x10^-19J) I get confused whether to times or divide by this.

Thanks!

 

[SteamKing]

The mass of a pion is 2.5x10^-28kg.
Calculate the mass of a pion in Gev/c^2.


I really don't understand how to do these, as I always divide/multiply the wrong numbers etc.
Does anyone have any ways to remember which way round you do it? (1eV = 1.6x10^-19J) I get confused whether to times or divide by this.

Thanks!

How would you calculate how much energy equivalent is in the mass of a pion? What formula would you use?