No fooling us, Duolingo Russian TTS. We know you were born in 2016. Вы родились пять месяцев тому назад.
Oh, there must have been. But the Duolingo Russian course was actually only a few months old back at the time of my comment. Thx for your upvote and laughs!
A summary of the useful comments buried below:
тому is redundant here, but popular in native Russian speek.
My theory: Since назад only means "backwards", тому назад originally meant "backwards (in relation) to this (point in time)" when the starting point - from which to count back the period in question - was stated in a preceding sentence only. Like English "prior to this".
But nowadays, Russians just keep the тому for the sake of a flowing speech, even when the reference point for the back-counting is obvious - the present day in our example.
No difference. Without this word this sentence has completely the same meaning.
Would one sentence be used over the other for a particular situation? One more formal?
The choice with "тому" is more colloquial and without this one it is more formal.
It's interesting that the long version is the informal one. Usually languages work in the other way.
I can give one example. In Polish some people prefer (at least in the spoken language) to make their sentences longer inserting pleonasms (this applies for the written language, too), particles ("-że" added to words as a means of emphasis) and repetitions.
"I saw it yesterday." "Widziałem to wczoraj" "Ja żem to wczoraj widział" (an example sentence you may hear in a tv series parodying that kind of people, it's not just "colloquial Polish", it's bad Polish, it also presents an example of expressing the past tense in a bad way, with a weird "że+personal_ending" pseudo-auxiliary verb)
"What did you ask him about?" "O co go zapytałeś?" "O co żeś się go zapytał?" ("pytać się" isn't incorrect but I don't consider it a very literate form).
This tendency of making reflexive verbs out of transitive ones seems to be actually quite popular in casual speech (even without this evil "że+ending"), so some people would say "pytać się" instead of "pytać" or "wracać się" instead of "wracać" (again, "wracać się" is not a literate form).
Some people would overuse the word "zapytanie" ("a query") because they think that "pytanie" ("a question") is not enough. Some would use words they don't know to make their language seem more fleshed out ("tudzież" meaning "as well as" used as "or", "czy też"), ("bynajmniej" meaning "not at all" used as "at least", "przynajmniej").
To sum it up, I would say that in casual speech the language may tend to shorten, but casual doesn't necessarily mean colloquial. In colloquial language people would stack up words wanting to say more even if that wouldn't mean that what they say conveys any more meaning. And even a correct usage of some more complex structures might be preferred in colloquial speech or writing, like probably this example in here, just to preserve some kind of flow of speech.
Technically, hundreds of thousands of 5-year-olds learn Russian every year!
блин, они лучше говорют по-русски, чем нас. The rub is, they're better at it than we are.
In this case "тому" has the meaning "from this moment of now" / "before". And I think this sentence doesn't need it neither in English nor in Russian. Because "я родился пять лет назад" is absolutely correct. The choice with "тому" is more native. But if you want to use this one in this task you should translate "тому" in English and you would face a problem that nobody says in English this way.
"Тому" has many meanings in Russian. But in this case when it is used with periods of time and the word "назад" it is referring to any period of time of hours, days, years, etc. until now, before.
Neon_Iceberg, it looks like you are a Russian native speaker that's why I want to ask you: WHY "тому" which is Dative for "тот" or "то"? I thought that "назад" takes Accusative Case. Please explain if you are so kind.
You can say this phrase without this word because it is redundant, it's an old fashioned and colloquial. This kind of expression (with this word) looks like a part of a fairy tale, but you can hear this word from your interlocutor in modern speech, so that is why this word is in this course. I do not think that this word is subject to the General rules of forming of sentence structure. It is an exception.
It reminds me of "нету" which apparently is also colloquial and it is not in a particular "падеж" . I am always looking to determine the case on which a Russian word is, so I can remember it easily. In this case, I will have to learn it by heart.
I understood this to mean "I was born five years before that". Just wondering if "тому" in this question can only be understood as now in time like it was mention in some of these comments.
Does anyone know where this expression came from? I know its idiomatic but I still find it hard to understand (with the dative case being used and all).
My Russian teacher said that it is a remnant from older language that uses the expression с тех пор with the тому (I think). She says you can still find this language in fairy tales. Sorry I can't give you a more complete answer.
is this an authentic sentence of a five year old Russian asked about his age?
this task does not work!!!! it does not add a progress....Who does have seems problems?