When I needed to calculate the radius of a turn in order to fly a safe low level demo I divided the square of my indicated speed by 10 times the reading I intended to use on the g meter.
I offer four advantages for this method:
The answer is in feet.
No conversion of units is required
You barely need to know how to spell maths.
The answer is 13% pessimistic which keeps you out of trouble with the display line even with an on crowd wind (and or your off days)
Worked for me
JF