Septilion or Septillion: How To spell?
The word Septilion is misspelled against Septillion, a noun meaning "According to the French method of numeration (which is followed also in the United States), the number expressed by a unit with twenty-four ciphers annexed. According to the English method, the number expressed by a unit with forty-two ciphers annexed. See Numeration."
Septillion has double "ll" is mispronounced as "l"Remember double 'LL' in between the strings septi & ion which should not be misspelled with single 'L'
Wrong Spelling:  septi-l-ion  Correct Spelling:  septi-ll-ion 
Find more incorrect spellings of Septillion to spell right way.