For JAR exams use
R in meters = (0.51 x TAS) ^2 / g (tan bank ang)
Where TAS is in knots and the 0.51 converts this into m/sec.
Or use 0.515 if you want to be a bit more accurate.
Remember to multiply the TAS by 0.51 before you square it. The mathematically challenged often square the TAS then multiply by 0.51. This does not work!