Old Smokey ,
your formula is of course right when you are looking for a way to convert a gradient into the required fpm.
And of course yours is the correct answer to wilcolucas question.
But , if you take a close look, the formula I gave is one to get the feet per NM, not the fpm.
So picking up your example with 120kt GS:
120 kt GS ---> 2 NM/min
Gradient of 6% ---> 360 ft/NM
Multiplying 360 ft/min by 2 gives the fpm.
So, I admit, you gave the correct answer to the original question. The formula I gave is nevertheless correct.
Cheers,
DBate
Edited to say that JABBARA was by a minute faster with his reply