"That is my phone number."
I wish I knew... That's what I put. I don't understand the difference in using 这 vs 这个 vs 那 vs 那个 .
there is not much of a real difference when actually speaking, technically "ge" is a measure word and functions sort of like an English article (but def not equivalent!) in the sentence but does not actually change the meaning
My understanding is 那个 or 这个 are used if followed by a noun, or to say "this one" or "that one" in general.
个 is a classifier of numbers. So literally That one (number) is my phone number.
This makes sense. But you have to agree the Chinese sentence doesn't make sense contextually.
You can say 那是 is a more natural way to say it rather than 那个是; Yet I don't see why 那个是 would not make sense contextually. If someone has 2 pieces of post-it on the fridge, one having his phone number written on it, it is still possible that he would use this sentence. It does not sound weird to me.
This makes sense. But I think the context matters here. So, without context, 那是 should have been accepted here
I don't understand the use of zhe or zhe ge or na vs na ge. I can't learn it from this app...
"ge" is called a "classifier". These classifiers are used in written but can sometimes be omitted in spoken chinese. Although the concept is difficult to understand, you can understand them as "measurement units". For example, the classifier for books is "ben", which can be translated as "volume": "一本书": one tome/volume (book). For more information you can check wikipedia: https://en.wikipedia.org/wiki/Chinese_classifier
Ge is a measure word in china we have many measure words in place, which you have to learn.
Ok, "That is my phone number."... correct is "Na" (far) and not "zhe" (close) because I'm more likely to point to it on a billboard sign than to hand it on a piece of paper when offering the sentence to someone? That does not make sense to me. Why isn't "Zhe shi wo de dian hua" better than "Na ge shi wo de dian hua"?
It is possible. Imagine your number is written down on a price of paper and the person you are talking to is closer to it than you are, say, when you are talking on the phone.