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A comment on Many elementary teachers don’t understand math, and it makes them anxious. Parent comment

Re:Many elementary teachers don’t understand math, and it ma... by billfruit on Saturday November 30, 2019 @08:51AM (#21669945)
Well if long division is unintuitive, the procedure to compute square-roots by hand is even more mysterious, as if it has transcended dealing with numbers and instead become a symbolic manipulation. Thankfully it is something I never had to apply, even once in adult life till now.
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Re:Many elementary teachers don’t understand math, and it ma... by hervature on Saturday November 30, 2019 @09:45AM (#21670170)
How do you compute square roots by hand? Isn't it just a rudimentary root finding algorithm?
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Re:Many elementary teachers don’t understand math, and it ma... by gshubert17 on Saturday November 30, 2019 @10:51AM (#21670436)
The calculation of the square root, relies on this result from squaring a number N = 10d + e (that is, single digits d and e, but d is in the 10s place):

NN = (10d + e)(10d + e) = 100dd + 20de + ee

Group the digits of the square by two, and add extra values to the "divisor" so that the extraction of the square root in effect undoes the squaring above.

See, for example, https://sciencing.com/calculate-square-root-hand-5081134.htm...

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Re:Many elementary teachers don’t understand math, and it ma... by jonsen on Saturday November 30, 2019 @10:31AM (#21670359)
Square Root By Long Division:

https://www.solipsys.co.uk/new/SquareRootByLongDivision.html

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Re:Many elementary teachers don’t understand math, and it ma... by all2 on Saturday November 30, 2019 @10:06AM (#21670249)
The only by-hand method for finding roots I know is "Newton's Method". I think I learned this in pure calculus?

https://en.m.wikipedia.org/wiki/Newton's_method

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Re:Many elementary teachers don’t understand math, and it ma... by chongli on Saturday November 30, 2019 @10:45AM (#21670406)
The older method is attributed to Hero of Alexandria [1].

[1] https://en.m.wikipedia.org/wiki/Hero%27s_method

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Re:Many elementary teachers don’t understand math, and it ma... by billfruit on Saturday November 30, 2019 @10:27AM (#21670349)
There is a method known as the the method of 'long-division' for finding the square root, that was what I was alluding to.
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