It does depend rather on things like your accent, how you asked, word order, etc. Did you say "170" as in "one seventy" or as "one hundred [and] seventy", for example? It's a bit of idiomatic usage for English speakers to treat three-/ four-digit numbers as if they were made of smaller ones. If Mr Polish Man didn't know this it doesn't mean he's not studied English -- just that he hasn't reached the proficiency of a native speaker yet and is perhaps too bound by the English he's been taught in lessons.
One of my all-time most embarrassing moments came when talking with a French speaker, from one of the African Francophone countries, I don't remember which. Anyway, I told him that I had been studying French for seven years at high school. He then asked me, quite naturally, "Sy oo que tu letudee le frans 'ay?" or something. I couldn't understand a word. And then realised that, he was saying "C'est où que tu étudies le français ? " which is a word order I had never encountered in my life but is asking an entirely obvious question. Red-faced, I told him. And then felt awful.
Learning a language, and being able to converse with a native speaker, are two entirely different skills. Never underestimate how hard it is to learn a language. Especially English, because the "rules" that foreigners learn about English are almost universally ignored by the natives -- leaving even those who have studied it in some depth floundering when they meet a native.