There seem to be a few options:

OPTION A

Your example of E-0015058 looks very like 1deg 50' 58"W, where the number follows the format ("E-" = W) DDDMMSS.

OPTION B

Try a few more examples, if you can, to see if the MM and SS figures ever exceed 59. If they do, then the number may be in DDD.DDDD format. If this is the case then remove the first three digits, these being the value in degrees, i.e. 001 degrees.

Take the rest of the number, precede it with a decimal point and multiply by 60. i.e. 0.5058 x 60 = 30.348

Remove the digits in front of the decimal point, these being minutes, and multiply the remainder by 60 to give seconds. i.e. 0.348 x 60 = 20.88 (roughly 21seconds).

Thus E-0015058 would represent 1 deg 30' 21"W

OPTION C

Alternatively, E-0015058 could represent 0.0015058 of 180degrees = 0.271044degrees = 16.26264minutes = 0deg 16' 16"W

My money would be on Option A.

Your calculations using 15960 seem odd. If it were a valid factor, it should be divisible by 60 and leave a sensible number. Although it can be divided cleanly by 60, the result is 266 - not a sensible number.

Are you sure that the number shouldn't be 1

**7**960

**00**? This being 179deg 60min - or 180 degrees. Even then, I can't see the point of it, especially as it's not in a format that you can just plug into a calculator (unless you have DMS input).

If you want to make converting MGRS to lat/long easier, you could try this freebie bit of software:

http://www.mentorsoftwareinc.com/FREEBIE/FREE0100.HTM