Q. Where can I find the population of a major world city such as Paris or London?

Try Statista or WolframAlpha.

Access Statista from Databases A-Z.

Once in Statista search for Paris and look for the "Global Business Cities Report".

Go to https://www.wolframalpha.com/ search for >population AND Paris<. Take note of the date of the information and where the information is credited from by clicking on Sources and then External Sources. 

Please contact the Reference Desk for further assistance.