@Nyoei The most commonly used ones you really need to know would be the following:

π (pi)

e (euler's number)

i (imaginary number)

and to a lesser extent φ (phi, golden ration)

Now if you want to include physics and not just pure math the list of essential constants is quite large.

As a side note while √2 is a very important number and worth exploring it isny usually represented as a constant in terms of notation. It is however called pathgoras' constant.

@Nyoei Eulers identity is cool and all but not the best way to understand those constants.

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@Nyoei Well there is absolutely no advantage to memorizing digits other than practice i memorizing stuff. Just memorize a fractional approximation.

22/7 is off from pi by only ~1/791

If that isnt accurate eough then 355/113 approximates pi within ~1/3000000

Both of these are far more accurate than any digits you could memorize.

@Nyoei Also i had the same experience with many teachers in my life sadly.

The Oddity@Nyoei@qoto.org@freemo That is mind boggling. I hate fractions, but that is kind of beautiful. When it comes to working out stuff for engineering things I'd use a computer, but that has a rather lovely degree of precision there. I wish I was stronger with my maths. I have problems with things I can't understand at the root which makes learning incredibly hard for me.

I had a lot of parroting teaching at school with not much explanation as to why things were the way they were. It's not very helpful for people like me so I fell behind on the things I couldn't understand the rules for. I spent a lot of time in the library trying to work out why things were the way they were. Maths at least, once you get the rules in your head, is beautiful:)

I really pity my lecturers...