Trying to learn only 100 words of a language seems to me a shortcut. And I don’t believe in shortcurts. I mean, if you wanna have basic conversations (let’s say using 500 words), then you should know at least 5 times more (2500). Why? because if there is a change on the topic, then you’ll probably understand the new vocabulary used. Besides, it’s weird to ask to other person to use only very basic vocabulary (unless you just want to order a bear)