Here's how you can figure that out:
* Identify the infinitive: The infinitive form of the verb is *augere*.
* Remove the infinitive ending: The infinitive ending in Latin is *-ere*. Removing this from *augere* leaves you with *aug*.
* Add the present stem ending: The present stem ending in Latin is *-o*. Adding this to *aug* gives you aug-o, which is the present stem of *augeo*.
The present stem is important because it's used to form various tenses of the verb. For example, you can use the present stem to form the following:
* Present tense: *augeo* (I increase)
* Imperfect tense: *augebam* (I was increasing)
* Future tense: *augebo* (I will increase)