"take the last 2 digits of the year you were born plus the age you will be this year and it WILL EQUAL .... 111"

Not a coincidence that 111 should occur in 2011, nor that everybody should get the same result.

Here are the results that you will/did get in some other years:

2009: 09 or109 . Examples: Born in 2001, so 01+8 = 09. Born in 1991, so 91+ 18 = 109.

2010: 10 or 110. Examples: Born in 2001, so 01+9 = 10. Born in 1991, so 91+ 19 = 110.

2011: 11 or 111. Examples: Born in 2001, so 01+10 = 11. Born in 1991, so 91+ 20 = 111.

2012: 12 or 112. Examples: Born in 2001, so 01+11 = 12. Born in 1991, so 91+ 21 = 112.

2013: 13 or 113. Examples: Born in 2001, so 01+12 = 13. Born in 1991, so 91+ 22 = 113.

Here is the mechanism: If you were born in year 19xx or 20xx, then in that year you completed 0 years, and xx+0=xx. Then the next year, you completed 1 year of age, so xx+1=xx+1. Then the following year, you completed 2 years, so xx+2=xx+2. Etc. In general, xx+N=xx+N. In other words, with each successive year, both the year number and your age increase by 1, thus keeping "in step".

EDIT: I did not explain that well; I'll try again.

If you were born in year yyxx, where yy is either 19 or 20, then N years later, the year is yyxx+N and your age is N. So, the last two digits of the current year is xx+N; and the last two digits of your birth year plus your age is also xx+N. Now, someone born M years after you were born was born in year yyxx+M, and at that time his age was zero, so the last two digits of his birth year plus his age was xx+M+0, or just xx+M, which is, of course, equal to the last two digits of the current year at that time. Now, at year yyxx+N, the number of years elapsed since year yyxx+M -- when the younger person was born -- is N-M; and so his age is exactly N-M also. What will that younger person calculate for the sum of the last two digits of his birth year plus his age? This: (xx+M)+(N-M), which equals xx+N, which is the same number that you calculate for the last two digits of your birth year plus your age.