The number of subsets of $\left\{1, 2, 3, ..........9\right\}$ containing atleast one odd number is 

A={1, 2, 3 …… 9}

Number of subsets of set $\mathrm{A}=2^9$

Number of subsets with even numbers 2, 4, 6, 8 only

 Number of subsets with at least one odd number 

$$\begin{gathered} =2^9-2^4 \\ =512-16 \\ =496 \end{gathered}$$