After reading all of these posts, I still have no idea what your requirements are. What should this string be? Do you have an example of the input and output?

You may just be looking to use the %x format for sprintf, which takes a number and constructs a hexadecimal representation of it. But since you say 9210 is a hex number to begin with, I haven't a clue what this string should contain. A decimal representation of the number? Use hex. Otherwise be more specific.