Find an irrational number between 0.1 and 0.19.
0.1 and 0.19 are two rational numbers, as it is terminating.
We know, between any two rational numbers, there are infinitely many irrational numbers.
An irrational number has non-terminating non-recurring decimal expansions.
Then irrational number between 0.1 and 0.19 can be 0.1010010001....
Similarly, 0.13030030003... is also an irrational number between 0.1 and 0.19.
NOTE:
These are some of the possible answers. It might have different solution.