Hint : Consider the tenths place
We have to find which is greater
$0.099$ or $0.19$
To find the greatest number we will be considering the tenths place of the number.
The tenths part of $0.19$ is $1$ and in tenths part of $0.099$ is $0$.
We see in above two numbers that tenths part of $0.19$ is greater than tenths part of $0.099$.
Since one is greater than zero.
We get $0.19$>$0.099$.
Hence $0.19$ is greater than $0.099$.
Note :- In these types of questions of finding greater numbers we can consider the numbering system which comes earlier is smaller or we can also consider ones, tenths, hundredths and so on places to find the greater number.