I do not understad why the program do not show the number values.
Even when I use N[xx].
How can I simplify this?
While this may or may not be closed, either as a “mistake” or as “not reproducible,” let me just point out the general approach indicated by my comment.
When Mathematica is not behaving as expected, especially on such simple input as the OP’s session-image shows, it is good to suspect that some invisible input might be causing the mischief. This may be checked by examining the FullForm of the expression, in this case,
Indeed, the response by the OP shows that somehow some empty text is a hidden factor multiplying one of the numbers:
Times[28.1743067577245`, Power[Plus[2, Times[4.904258335022924`, TextCell[“”]]], -1]]
Therefore this product is non-numeric and cannot be combined with 2..
Ironically, you have the characters U+200B ZERO WIDTH SPACE U+200C ZERO WIDTH NON-JOINER present in your answer from copying OP’s comments. This rubbish is inserted by SE in an attempt to insert line breaks into comments, but it doesn’t work for that purpose and results in contamination of comment code with invisible characters…
– Oleksandr R.
Sep 30 ’15 at 23:51
@OleksandrR. That’s pretty funny. Fixed (I think).
– Michael E2
Sep 30 ’15 at 23:58