When you are looking at your Gmail contact list, or address book, it will likely be smaller than the default number of contacts visible per page for a Gmail account, which is 100 (and also happens to be the "middle" value). If you like to see a smaller set of contacts at any given time, however, Google allows you to change that number to either 25 (the smallest number of contacts you can display per screen), or 250 contacts. This tutorial explains how to change how many contacts are displayed by Gmail on a single screen.
Follow these steps to increase or decrease the number of people shown from your Gmail address book, on one screen at a time:

100" is the default, but your Gmail account may show a different number if you or another authorized user has previously changed this value.
Tip: note that this setting only controls "pagination" - it does not affect the content of your address book in any way, only the subset of contacts you see at once, at any given time!