The following is help finding the operating system on an iPhone. Android help is further down the page
Locate and tap the 'Settings' App on your device's Home Screen.
Next find and tap the 'General' tab
Find and tap the 'About' tab
Now down the list find 'Version' in the left column. Your device's operating system version number is on the right column. No need to remember the numbers in the parenthesis.
Find and tap the 'Settings' App
Under 'System' Find and tap the 'About Phone' or 'About Tablet' tab
Find the 'Android Version' block and under that is your operating system's version number