That's because of an error in your calculation.
12C is 300,
lovely number 3E7 is 999,
max value 2-bytes, FFFF, is 65535,
max value 4-bytes, FFFFFFFF, is 4,294,967,295, same as max uint32.
05F5E0FF is 99,999,999, like in the save patches.
You don't add 'tens places' like pencil-and-paper...