Hendecaphobia

Hendecaphobia (from hendeca, Greek for "eleven") or Undecaphobia (from undeca, Latin for '"eleven") is the fear of number 11. The reasons for this fear of number is due to dark history associated with number 11 or digits that sum it to 11, especially terrorism. On 9/11 (9+1+1=11; which September 11 was the 254th day of the year (2+5+4=11)), Flight 11 and Flight 77 (77 is divisible by 11) crashed into the World Trade Center carrying 92 passengers (9+2=11) and 65 passengers (6+5=11), respectively. The total number of victims in hijacked planes is 254 (2+5+4=11). New York where World Trade Center was destroyed was the 11th state. There was the natural disaster that gives fear of number 11. The Indian Ocean tsunami occurred on 12/26 in 2004 (1+2+2+6=11) that killed 300,000 people.

Many hendecaphobes are afraid of terrorist attacks and would refuse to be in a airplane or any other mode of transportation that has number 11, a number divisible by 11 such as 66, or a number whose digits adding up to 11 such as 47. They would worry about disasters occurring to them when component digits in its date add up to 11, such as 3/17, 7/4, 9/11 and 12/26, or even a year whose component digits add up to 11, such as 2018. A more severe sufferer would move out of the house whose component digits in its address add up to 11.