The phrase "number of different purposes" refers to how many unique or distinct functions a particular object, tool, or system can serve. Full definition
The liver is actually our largest vital internal organ and it serves a number of different purposes including helping with digestion and ridding the body of harmful chemicals and toxins. (fitnessandpower.com)
The HCG hormone injection has been approved by the FDA for a number of different purposes such as fertility, but has still not been approved as a weight loss supplement. (banyanwellness.org)