Thretten or Thretteen: How To spell?
The word Thretten is misspelled against Thretteen, an adjective meaning "Thirteen."
Thretteen has double "ee" is mispronounced as "e"Remember double 'EE' in between the strings Thrett & n which should not be misspelled with single 'E'
Wrong Spelling:  Thrett-e-n  Correct Spelling:  Thrett-ee-n 
Explore spell check of Thretteen to spell without errors.