make a character array (hexval) about 10 characters long
set whole array to spaces
set hexval[9] to '\0'
set hexptr to 8 -- this will point into hexval to load the hex chars.
Read a line into an integer (intval) -- that's base 10.
Loop until that integer is 0:
    set hexval[hexptr] = remainder of intval/16 
    add 48 ('0') to hexval[hexptr]  -- this converts the integer value to a digit character
    if hexval[hexptr] > 57 ('9') add 7 -- value is now 'A' - 'F'
    decrement hexptr  -- to load the next hex digit
    divide 16 from intval -- to remove the hex val we just loaded
    End of loop