Quadrilion or Quadrillion: How To spell?
The word Quadrilion is misspelled against Quadrillion, a noun meaning "According to the French notation, which is followed also upon the Continent and in the United States, a unit with fifteen ciphers annexed; according to the English notation, the number produced by involving a million to the fourth power, or the number represented by a unit with twenty-four ciphers annexed. See the Note under Numeration."
Quadrillion has double "ll" is mispronounced as "l"Remember double 'LL' in between the strings quadri & ion which should not be misspelled with single 'L'
Wrong Spelling:  quadri-l-ion  Correct Spelling:  quadri-ll-ion 
Check more misspelled words of Quadrillion to spell it correct.