Finding the square root without a calculator (1 Viewer)

[Sparcod]

I know this has nothing to do with school but its just for interest. Is there a way of finding out the square root of say,2, without a calculator? i know theres long division involved


anyway, on my calculator sq root of 2 is 1.4142135 but can i do that without a calc?

 

[badhairday]

one way you can do it is graphically.
Draw a right angled triangle with two sides 1cm each and the hypotenuse should equal the sqaure root of two.
Although not as accurate, i think this is how they used to do it in ancient times

 

[Trev]

one way you can do it is graphically.
Draw a right angled triangle with two sides 1cm each and the hypotenuse should equal the sqaure root of two.
Although not as accurate, i think this is how they used to do it in ancient times

not "should" it WILL equal the square root of 2 (unless ur a shit drawer like me )
but how does this let you find out wat root 2 is without a calculator ey?
(ps. why bother trying to work it out anyways...)

 

[badhairday]

not "should" it WILL equal the square root of 2 (unless ur a shit drawer like me )
but how does this let you find out wat root 2 is without a calculator ey?
(ps. why bother trying to work it out anyways...)

you measure the length of the hypotenuse of the triangle. It'll give you the rough value of root 2 without a calculator.
but dont know why you would want to work it out anyways, now that we have technology.

 

[Dreamerish*~]

oh i learnt this in year7 (we had a very challenging math teacher)
it's really hard and time-consuming and takes up a lot of space, but yeah, there's a lot of long division.
i can't really show it here... but you don't really need to know this do you?

 

[Trev]

teach me? chances are my calculator will screw up in the exam
my friends calculator is cut in half just above the screen, so u can take it off and it hangs by its wires connected to the battery - and he still wants to use it for hsc heh

 

[Dreamerish*~]

lol i can't write it up though.
my calculator actually stuffed up during my math prelims. i was so scared but the teacher came and fixed it
don't worry, if your calculator stuffs up they'll give you another one
or go to your teacher now and warn them about it so they'll have a spare just for you lol

 

[shannonm]

http://www.newton.dep.anl.gov/newton/askasci/1995/math/MATH066.HTM

 

[Slidey]

It sort of involves long division. The way I was taught to extract square roots ('involution' it is called) looks similar to long division at a glance. The method I use is NOT an approximation method. It will give you the EXACT answer, correct to n decimal places. Obviously you can't go forever because of the whole irrationality thing.

Involution is as time consuming as long division, but practice can make it a fairly quick exercise.

You can learn involution here: http://www.qnet.fi/abehr/Achim/Calculators_SquareRoots.html

Pardon the crazy European guy. He means well.

Another site if you are finding the first one confusing: http://www.nist.gov/dads/HTML/squareRoot.html

 

[Trev]

lol i wasnt really serious, i dont see the point of working out the square root of stuff without a calculator - i looked at that site, how can you be bothered to learn that stuff? =S looks confusing i dont understand either lol