The new tags "number" and "theory" were created at the same time tagging the same question leading me to believe that they are meant to be "number-theory". They do not contribute anything as tags so removing them may be a good idea.
Useless, duplicate, or misspelled tags are created often, and should be removed from questions. Users with 2K rep interested in having a somewhat sane tag system may want to look at the list of new tags regularly and deal with miscreations such as
- number created 1 hour ago
- theroy created 1 hour ago
- differantiability created 5 hours ago
- solve-problem created yesterday
- statistical created yesterday
Just remove such things from questions, replacing them with appropriate tags. Having no questions left, a tag dies within 24 hours.
If you are unsure if the tag is useful or not, begin discussion on Meta, for example in Tag cleanup 2014.
[I dealt with those listed above, except differantiability was already gone by the time I saw it.]