You should know the implicit meaning of the prefixes of units of measurements. Let's take for example, the unit of meters. When you say kilometers, that would be 10³ of a meter. When you say megameters, that's 10¹⁰ of a meter. So, if a unit is 5.69×10¹⁰ meters, you can just express that into 5.69 megameters.
