This week I said to my students "how many digits do you use to approximate non-exact square root?" Almost everyone said 2. Why? They did not know. My opinion it's because math teachers repeadely told them
*without any reason*...

@somenxavier so what's the reason? Googling "why two decimal places" didn't come up with anything!

@ccppurcell Really do you solve all your doubts searching in google? Why (if there is) we take 2 decimal places and not just 1? Is there any reason for that? Think it. 🤔 If we have a context (for example money problem) it could have sense, but if we have not this context, it's arbitrary because we don't care the error we take. But this is my opinion. What's yours? Thanks for answering.

@somenxavier seems like you are shaming me for not knowing something you know. That isn't very good pedagogical practise.

@ccppurcell no. I did not shame it. Sorry if you felt it. I just want to think yourself

@somenxavier perhaps I was a little unfair, let me explain: to me "really do you do xyz?" has a quite aggressive, condescending tone. No I don't solve all my doubts with google. I am a mathematician, of course I thought about it but it seems you agree that it is arbitrary. That wasn't clear from your initial toot. I thought that there might be some *historical* reason for 2d.p. Why shouldn't I use google to find out? I can't possibly deduce history from first principles.

@somenxavier for the record, to me it seems that approximating (e.g.) root 2 in base 10 is more or less arbitrary. But I was also taught that it should be 2d.p. by teachers, so I googled it. If you are this shitty to your students I feel sorry for them

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