Thirten or Thirteen: How To spell?
The word Thirten is misspelled against Thirteen, a noun meaning "A symbol representing thirteen units, as 13 or xiii."
Thirteen has double "ee" is mispronounced as "e"Remember double 'EE' in between the strings Thirt & n which should not be misspelled with single 'E'
Wrong Spelling:  Thirt-e-n  Correct Spelling:  Thirt-ee-n 
Find more wrongly spelled words of Thirteen to spell it well.