iOS 7.1 or earlier
1) Open the Settings App. In the menu, select General and select Usage.
2) In the list of apps, find the app in question and select it. You may need to select Show All Apps to find the app you are looking for.
The next window will display the version number, app size and how much data is being used.
iOS 8 or newer
1) Open the Settings App, Select General and select Usage.
2) Under the Storage heading (not iCloud) Select Manage Storage.
3) In the list, find the app in question and select it. The version number along with the amount of storage that is being used will be viewed.