The Little House on the Prairie has a total of 202 episodes, if you include when the series changed its name from Little House on the Prairie to Little House: A New Beginning for the 9th season and the three special length episodes that completed the series the following year.
If you only include the number of episodes when it ran under the Little House on the Prairie name, prior to Michael Landon departing the show, then there are 180 episodes over 8 seasons.
You can find the full Little House on the Prairie Episode Guide here.