*For large values of three, and small values of pi.*
If you don't need the accuracy (was that temperature 12 000 000 C or 12 000 000 K?), and can get away with an approximation to an OrderOfMagnitude

?,

**pi = 3** and

**pi^2 = 10**.

Or rather pi^2 = g; cancels out nicely in physics courses.

*But for such approximations, g also equals 10. :-)*
See also

ValueOfPi

*"The value of 'pi', recited to the length of one decimal digit...*
"3".

*There. That's it. ;->*