To find the total file size of 6 pictures, we can multiply the size of each picture by the number of pictures:
\[ \text{Total size} = \text{Size of each picture} \times \text{Number of pictures} \]
\[ \text{Total size} = 2.4 , \text{megabytes} \times 6 \]
Calculating this gives:
\[ \text{Total size} = 14.4 , \text{megabytes} \]
Therefore, the total file size of 6 pictures is 14.4 megabytes.