How many Mormons voted in 2012?

Answer 1

You are not required to register your religion when you vote, nor does the Church of Jesus Christ of Latter-day Saints (the 'Mormon' church) have any way of keep track of how many of their members vote. Most Mormons live outside of the United States, and their home countries may or may not have held elections in 2012.

Essentially, it is impossible to know, or even to guess, at a number. Church leaders encourage members worldwide to be involved in elections in their respective countries, but do not keep track of member participate in the political process.