Incorrect spelling, explanation: forteen is incorrect because 14 is four and ending -teen. Therefore there should be a letter u in the first part of the word: fourteen. Although forteen is an incorrect spelling of the number 14, forty is the correct one for the number 40, and this is probably the origin of this mistake. We do not know why forty is spelled without the letter u (it didn’t use to be!), so it’s even more confusing. However, it is worth remembering that the correct spelling is fourteen.

Correct spelling, explanation: cardinal numbers from 13 to 19 are spelled with a -teen ending. We simply add this ending to the root number; in this case to number four, receiving the word fourteen. The mistake with the spelling forteen may be caused by the fact that the number 40 is spelled without u in four: forty. We do not exactly know why this happened to this word, but this spelling has been present in English since the 18th century. This, however, does not apply to fourteen, which is still spelled with u.
 
Definition of fourteen:
numeral, a cardinal number between 13 and 15
Sarah celebrated her fourteenth birthday with a party at the local roller skating rink, complete with cake and balloons.
The new office building will have fourteen floors.
The baseball game ended in a tie at fourteen-fourteen, forcing the teams to play extra innings to determine a winner.

Incorrect spelling

Incorrect spelling

Incorrect spelling

Incorrect spelling