Why Are There 100 Senators In A Senate?

Not really sure - someone must have decided that 2 senators for each of the 50 states, irrespective of the size or population of those states, was about right.

Perhaps they don't really wield much power compared to ordinary congressmen, so numbers aren't really important ?

The US Constitution calls for two senators from each state. Presently we have fifty states, thus one hundred senators. Our founding fathers thought this was practical.

There are two from each state a democrat and a republican....hope this helps you good luck

So that there can be enough people to express their ideas and so there can be a round number that is easy to manage.-Trey

It isn't necessarily a Democrat and a Republican.  It is whatever party the people elect.  Maybe D&R, 2 D's or 2 R's, and a few States have independents also.