Calculating characters from the sum of ASCII pairs I have a series of messages (limited to only a-z and A-Z) that are encoded such that the sum is taken of every two ASCII values and concatenated. For instance, the message hello would be decomposed into the pairs he, ll, and o which would then become 104 + 101, 108 + 108, and 111 which finally is output as  205216111. Each pair is guaranteed to be 3 digits by zero-padding. 

Is it possible to trivially decode this final number back into the plaintext? The words are in plain English and each word is capitalized. So far I have attempted to enumerate all possible permutations and identify words from a dictionary list but this has proven to be rather tedious with short messages alone.
It would be impossible i think. But if you consider evolving the encrypion system such as changing pair like  : "he","el","ll","lo","o" it would be way to easy to decrypt.