Author Topic: Taking square roots by hand  (Read 3595 times)

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Offline squidgetx

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Taking square roots by hand
« on: February 06, 2011, 08:09:01 pm »
Why would you need this??? We have calculators! ;)

Anyway, thought some of you guys would appreciate this ;)

edit: holy, massive picture x.x
« Last Edit: February 06, 2011, 08:11:00 pm by squidgetx »

Offline Binder News

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Re: Taking square roots by hand
« Reply #1 on: February 06, 2011, 08:16:00 pm »
LOL. I love it. Might just show it to my math teacher.
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Offline Xeda112358

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Re: Taking square roots by hand
« Reply #2 on: February 06, 2011, 08:41:50 pm »
Ah yes, this is a very nice method. I've been doing this since 7th grade :D I happened to have a trig book from the 50's, no electronics, and a whole summer vacation of having fun with math.

In binary:

Let:
A=Result
B=Remainder

Initial:
d=0
b=01 01.00 00
a=0

Cycle 1
;shift upper two bits in b to D
  b=01 00 00 00
  d=00 00 00 01
2*A
 ;A=00 00 00 00
A→C
 ;C=00 00 00 00
2*C+1
 :C=00 00 00 01
cp C,D
 if C is less than or equal to D
  D-C→D
  ; D= 00 00 00 00
  A+1→A
  ;A=00 00 00 01
Repeat
;shift upper two bits in b to D
  b=00 00 00 00
  d=00 00 00 01
2*A
 ;A=00 00 00 10
A→C
 ;C=00 00 00 10
2*C+1
 :C=00 00 00 11
cp C,D                              ;C is greater than D
x if C is less than or equal to D   ;False
x  D-C→D                            ;Not Executed
x  ; D= xx                           ;""
x  A+1→A                            ;""
x  ;A=xx                            ;""
Repeat

The first two bits calculated in this case is the integer part and after that all the bits are the fractional part (in binary).

EDIT: Those ;D are supposed to be ; D. grrr...

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Re: Taking square roots by hand
« Reply #3 on: February 06, 2011, 09:40:06 pm »
Nice, I always wondered how to make square roots by hand. Thanks :D

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Re: Taking square roots by hand
« Reply #4 on: February 07, 2011, 07:31:35 am »
The square root one is a specific example of the Shifting nth root algorithm
You can also find any higher roots, and in any base! ;D
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