Explain this line of code!? : sprintf(buffer, "%d", argv[1][strlen(argv[1])-1]);

Hi experts,

I am pulling apart some old c code at work and have come accross a line I have litle idea about, hopefully it will be completely obvious to you guys.

The line is this:

sprintf(buffer, "%d", argv[1][strlen(argv[1])-1]);

The value of argv[1] is UK12398
Buffer evaluates to 56

I can't see how buffer evaluates to 56, can someone explain to me exactly the process that it goes through to get that number from UK12398

Many Thanks in advance
Jamie.