21
There are 696 episodes of classic Doctor Who (not including the TV movie), comprising 157 different stories. However a large number of these episodes (108 in total) are 'lost' and it is thought copies no longer exist. The First Doctor: 29 stories (134 episodes) The Second Doctor: 21 stories (119 episodes) The Third Doctor: 24 stories (128 episodes) The Fourth Doctor: 42 stories (172 episodes) The Fifth Doctor: 20 stories (69 episodes) The Sixth Doctor: 8 stories (31 episodes) The Seventh Doctor: 13 stories (43 episodes)
42
Up to Journey's End 198 stories 751 Episodes
there is 22 episodes
The second season of "Damages" has 13 episodes.
There are 696 episodes of classic Doctor Who (not including the TV movie), comprising 157 different stories. However a large number of these episodes (108 in total) are 'lost' and it is thought copies no longer exist. The First Doctor: 29 stories (134 episodes) The Second Doctor: 21 stories (119 episodes) The Third Doctor: 24 stories (128 episodes) The Fourth Doctor: 42 stories (172 episodes) The Fifth Doctor: 20 stories (69 episodes) The Sixth Doctor: 8 stories (31 episodes) The Seventh Doctor: 13 stories (43 episodes)
The Seventh Doctor appeared in 43 episodes (comprised of 13 stories).
The Fifth Doctor appeared in 69 episodes.
24
42
31
415 separate stories.
Up to Journey's End 198 stories 751 Episodes
There have been 753 episodes in Doctor Who.
The Daleks appeared mostly in the first and second doctor's era. If you count "The Dlek's Master Plan" and "Mission to the Unknown" as separate stories, they have appeared in 14 stories.
Expanding your question to 2008 (as it is now as I'm answering, so up until the last episode of Season 4 of the new series, Journey's End)... There have been 202 stories (if you include the unfinished Shada) comprising 757 episodes. And if you don't count Shada, 201 stories 751 episodes.
There are 13 episodes in every season of Doctor Who.