It seems like a simple mathematical equation, but it is, in fact, one of the most profound and sublime, describing the purpose of life, and how to rectify all that goes wrong in Creation.

Other number 11 facts on the 9/11 event:

The date of the attack: 9/11 - 9 + 1 + 1 = 11.
September 11 has 9 letters and 2 numbers: 9+2=11.
The number 911 is the telephone number for emergencies in North America.
September 11th is the 254th day of the year: 2 + 5 + 4 = 11.
After September 11th there are 111 days left to the end of the year.

The first plane to hit the towers was American Airlines Flight 11.
The Flight 11 call letters were AA11: A=1, A=1, AA=11.
Four of the hijackers on flight AA11 have the initials A. A. for their names: AA=11.
The fifth AA11 hijacker was the pilot, Mohamed Atta, 11 letters, and AA in last name.
Flight AA11 had 92 people on board - 9 + 2 =  11.
Flight AA11 had 11 crew members - 2 pilots and 9 flight attendants.
The target of Flight AA11 was in New York City -11 letters.
The State of  New York was the 11th State added to the Union.
Manhattan Island was discovered on Sept. 11, 1609 by Henry Hudson -11 letters.
Trade Center is 11 letters, and Skyscrapers is 11 letters.
World Trade Center Towers is 22 letters - 2 x 11 =22.
The WTC Twin Towers - standing side by side, look like the number 11.
The WTC Towers are each 110-storeys high.
The first WTC tower hit (North Tower) collapses at 10:28 A.M. -1+2+8=11.
The 1st Fire Unit to arrive to the WTC towers was FDNY Unit 1. Unit 1 lost 11 firemen.
The WTC towers collapsed to a height of 11 stories.
After 99 days of burning, NYC declares the WTC fires are extinguished - 9 x 11 = 99.
The World Trade Center fires burn continuously for 99 days, between September 11, 2001 and
December 19, 2001. The World Trade Center fire is the longest burning commercial fire in U.S. history.
On September 7, 2002, NYC Medical Examiners announced the revised official
death toll from the World Trade Center attacks was 2,801 - (2+8+0+1 = 11).
On the morning of September 11, 2002 the names of 2,801 victims were read at a Ground Zero
Ceremony. It took 2 ½ hours to read all the names.