Translation:I will learn where such wardrobes are sold, and buy one.
They are different forms of the same verb "узнавать". It has two similar meanings: "to find out" and "to recognize". The stress varies only with the change of the tense:
- I learn many new things - Я узнаю много нового. For example you can say that while watching a interesting TV show.
- I will find that out tomorrow - Я узнаю это завтра. For example you can say that if there will a meeting with a counsel on the next day.
- I recognize him - Я узнаю его
- I will recognize him from the thousands - Я узнаю его из тысячи.
Yes, the amount is not defined precisely, but that is still a complete phrase. Depending on the context it may be either one or several wardrobes.
For example the wife asks her husband: "Please buy 26 quail eggs for our family dinner". In this case husband would easily answer: "Я узнаю, где продают такие яйца, и куплю."
Such answer would fit perfectly meaning 26 eggs. The sentence contains the word "such" which uniquely says there IS some context.
And even with no context it's quite OK to say in such way. It means that the number is selfimplied and does not need clarification.
Still there could be also an object in the end defining the quantity, it's also rather useable way of saying.
I think the phrase is OK even without context. I would easily say so with a strong intonation on the word "куплю".
And BTW if you say "Куплю себе" it also doesn't define the number, so all you're trying to say is that the sentence is not idiomatic. The user was asking how to understand what is the number of wardrobes bought.
In english you have to say "buy one" because the verb requires an object. There is no cases in Russian when a verb cannot stand alone. Thus if the number of things bought is not important or obvious we usually don't use excessive word. But you can specify if you need:
- Мне нужно 5 машин - пойду куплю - I need 5 cars - I'll go and buy them;
- Мне нужна машина - пойду куплю - I need a car, I'll go and buy it (number is not defined, but the person is most likely talking of an adequate amount of goods - one for countable and a bunch for uncountable goods);
- Мне нужна машина - пойду куплю одну - I need a car, I'll go and buy one;
- Мне нужна машина - пойду куплю пять - I need a car, I'll go and buy five of them;
- Мне нужна машина - пойду накуплю - I need a car, I'll go and buy lots of them.
No, for this sentence the second case fits best. An ordinary people don't need several wardrobes. If it would be a dealer talking about wardrobes that he would resell later, he would you use the word "закупить" instead of just "купить".
I agree, that the original russian sentence is not perfect. I would definitely put it another way. At least I would add the word "myself" in the end, otherwise it's sounds a bit clumsy and unnatural:
"Я узнаю, где продают такие шкафы, и куплю себе."
But still even without specifiying the number, russian sentence does make sense, it is grammatically correct and is understandable.
However if you try to omit the word "one" in the english version, your sentence will be grammatically wrong.
Then it should accept both "buy one" and "buy some". It's not hard to imagine buying cabinets for a business that needs one in each office, or something like that. With no context, the exercise MUST accept both. Otherwise we are not learning Russian, we are trying to read the mind of a test writer.
In case you don't like Duolingo's pronunciation http://talkobamato.me/synthesize.py?speech_key=8d14f7d19a022fd0c9d64be6f91fec14
Truly word "узнаю" can have this meaning in addition to its main meaning. But not in this sentence. For example it could be in the sentence like:
"К тому моменту я уже узнаю, как это решить" - By that moment I will already have known how to solve it.
But this translation is very narrow. Moreover it does not contradict to the main translation, so you could just forget about it and make use only of the main one.