Guess the next number in the following series 1, 4, 5, 6, 7, 9, 11, ?

Answer 1

Answer 100

Because in these numbers its name not containing letter T. Next letter without T is hundred.
1 - one
4 - four
5 - five
etc..

But these numbers have letter T, so they are rejected.
2 - two
3 - three
8 - eight

Answer 2

These numbers doesn't contain letter T in its words.

The next number without T is HUNDRED.

1 = one
2 = two - rejected
3 = three - rejected
4 = four
5 = five
6 = six
7 = seven
8 = eight - rejected
9 = nine
10 = ten - rejected
100 = hundred

Answer 3

Twelve maybe?