It depends on what meaning you are trying to convey. 'Most' by itself means the majority of a group. 'The most' means the greatest/best/biggest - i.e. it's a superlative form. So, you can say 'most plants need sunlight' = the majority but not all, whereas, 'the most books I've ever read in a week is 4' = the biggest number.

The sentence needs a verb (action word) -- "Most simplified numbers" does not say anything about the numbers. To answer your question, "most" does not need "the" in front of it.

No, people will not be confused. Nat Ros is correct to point out that this is not a complete sentence. My assumption is that you wish to identify or discuss the numbers which have been most simplified: if so this is simply the name or identifier of a specific group of numbers, similar to "the results from our experiment". If so, strictly it should begin with 'the', but it is usual to omit this when time and space are limited, e.g. when writing notes, headlines, recipes and PowerPoint slides.