must do, have to do
Structure
- Verb[な
いく・て]・は・ならない
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In the meaning description for this grammar point, it says the casual equivalent of this is だめ. I couldn’t find it in the “Dictionary of Japanese Grammar” books or when I searched the grammar points on this site. Does anyone know where I can find an explanation/examples using だめ in this context? Thanks. 
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Hey 
だめ will later receive its own separate grammar point since it is on to-do-list. Bascially it is very simple to use, instead of ならない or いけない you just say だめ。
So:
Verb[なく] + ては + だめ
Verb[なければ] + だめ
Examples:
ミルクを飲まなくてはだめだよ！
You must drink milk!
めがねちゃんには本当のことを言わなくてはだめでしょ。
I think that you have to tell the truth to Megane-chan.
知らない人にお前はもう死んでると言ってはだめだよ！
Do not say"you are already dead" to unknow people! 
Remember that you can contract ては to ちゃ and では to じゃ。
ここで寝ちゃダメ。
Do not sleep here!
それは触っちゃダメ。
Do not touch it!
食べちゃダメ。
Do not eat it!
返事しなくちゃダメ。
You must reply!
勉強しなくちゃダメ。
You must study!
赤信号は止まらなくちゃダメ。
You have to stop at red light!!!
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This is so helpful! Thank you so much! 
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@mrnoone So it’s casual but looking for the long form… can you maybe add to the upfront hint whether you want the long or short version?
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Sorry for the long answer time 
I have fixed it! (and checked other sentences for that error)
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What’s the actual difference between N4: なくてはならない and N5: なくちゃいけない, since they both mean “must, have to”?
They are very similar, but the former has a more polite/formal nuance.
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Hi,
If bunpro considers いけない wrong, and then when I click to see correct answer it puts ならない.
Am I really wrong? Or it is acceptable?
Is there a way to know if Bunpro is expecting one or the other as an answer?
For instance, when bunpro wants the colloquial form, instead of putting it wrong, he just asks to enter a more colloquial form, without considering wrong the initial answer…
It should say in your review whether it wants long or short form followed by either いけない or ならない. They are separate grammar points with different example sentences and SRS progressions.
It will say it in the gap and after you start typing it should move above the sentence.
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Am I losing my mind or is " ３時半までに、銀行にいかなくてはならない marked wrong? It says “casual” but the tips suggest more formal? Or am I just confusing polite and formal?
First, ha! That’s funny. 
But, I think they’re looking for
いかなくてはならない
Which is considered more formal but still casual (not polite) verb form.
いかなくてはなりません
…is formal and polite.
(なる is also in the hint)
Yeah, the problem is the opposite of the English words “formal” and “polite” can be “casual”.
@Jake Maybe this could be “more formal speech” vs “more polite form”?
At the top of these questions is say
[long form て＋なる casual]
what does that mean? As in what are you trying to tell me with that?
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I’ll try my hand at explaining, sorry if it isn’t really clear :
So, there are a few things going on here. First up is the long form, which means the complete formulation of なくてはならない. This because there exist shorter forms of the grammar point, namely :
- なくちゃならない
- なくちゃ
The second thing going here is that it is the て - form, to make clear you must use なくてはならない instead of the form using the ば conditional : なければならない
Then the last thing to keep in mind is that you need to use ならない instead of いけない. This is simply due to it being the most formal structure you will encounter in writing.
So, add it all together and you get the grammar point なくてはならない.
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okay thanks! I was confused since I haven’t seen any of the other forms yet so I didn’t get what they were trying to tell me
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Also does this grammar point mean the exact same thing as N5 Lesson 9: 12/13
Because it kinda seems like it’s the same meaning just a different style of saying it.
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なくちゃ is indeed a shorter form of なくては（ならない ・ いけない）while なきゃ is the shorter form of なければ（ならない・いけない）
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Is the は in なくては（ならない・いけない）strictly required? I may be wrong, but I feel like I’ve heard some form of なくていけない or なくてだめ in Japanese media…?
There’s something that I don’t quite understand about this grammar point (and the similar なくてはいけない): what purpose does the は serve here exactly? Wouldn’t なくてならない effectively mean the same thing?
I think I must be missing something about the use of て form here, if somebody could orient me towards the relevant grammar point I’d be thankful.
Oh I just noticed that you asked the same question. Hopefully this time we’ll get an answer…