Does downloading apps on iPhone take a lot of data?

My internet plan is 8gb for four weeks and it only lasted a week or so. Usually is does not go this quickly. My room mate has recently got an iPhone and has started to download and use a lot of applications.

Do you think this is due to downloading and using apps? I have little knowledge on data usage ect

Added (1). Just to be clear - Does downloading applications on the iPhone take significant amounts of internet gbs?

Yes, because you only have an 8gb.

you will need a 32 or even a 64gb to store even more music, videos, media, apps, and data…

Yes, downloading apps on iPhone take a lot of data. Downloading a app uses the internet and uses data equal to the size of the app. For example, if you download an application which is of 8 MB, it will use 8 MB of your data to download.