hi
Here is solution to your problem.

I assume that you are doing coding in assembly language.

there is a method of subtraction for this.
suppose you have hex number in two registers say r1 and r2.
r1-msb
r2-lsb

now first you subtract 10000 that is 2710h from this.
lower byte first and then higher byte.
i.e
subtract 10h from r2 and 27h from r1.
increment a register each time you can subtract.
if there is a carry in subtraction then retrieve lsb bby adding
10h and subtract 1000 that is 03e8h and continue so on and increment a register each time you subtract without carry.

you should get ans by this method.

If you still have any questions there is a ready to use code in code library.