Square Roots

The Cat · 09-14-2004, 08:18 PM

Do any of you guys know how to find the square root of any number without using a calculator?

Parrakarry · 09-14-2004, 08:56 PM

Ehh, kind of. Gotta divide and average or something like that. My algebra teacher told me how, but I don't remember EXACTLY... here, lemme look it up.

Ah, here it is:

Quote:

To find sqrt of 5:

FIRST PROCESS

Step 1: Guess 2 (because 2*2=4, close to 5)

Step 2: Divide 5 by 2 = 2.5

Step 3: Find average of 2 and 2.5 = 2.25 (because (2+2.5)/2 = 2.25)

Step 4: Next guess is 2.25

SECOND PROCESS

Step 1: Guess 2.25

Step 2: Divide 5 by 2.25 = 2.22222222 (go 8 decimal places for accuracy)

Step 3: Find average of 2.25 and 2.22222222 = 2.23611111

Step 4: Next guess is 2.23611111

THIRD PROCESS

Step 1: Guess 2.236111111

Step 2: Divide 5 by 2.23611111 = 2.2360248

Step 3: Find average of 2.23611111 and 2.2360248 = 2.2360679

Step 4: FINAL guess is 2.2360679

Now CHECK your final guess with a calculator: sqrt 5 = 2.2360679

The Cat · 09-15-2004, 10:15 PM

K, thanks, because my calculator broke.

Still, I don't the idea of using trial and error to find a square root, but I guess it's the only method that works.

Parrakarry · 09-15-2004, 10:26 PM

Ahh, but it's NOT trial and error. That's the exact equation your calculator performs to do a square root, too. Just a lot harder. XD

dux_is_me · 09-15-2004, 11:10 PM

Dunno, but there's still "Calculator" on the Start Menu. Are you not using Windows or something?

UserGoogol · 09-16-2004, 01:34 AM

It's not an equation, it's an algorithm.

Hmnm, but I'm not sure if calculators and computers use that method. There's probably a faster method than your algorithm.

There's a long-division-esque algorithm explained here and elsewhere. It's much easier on humans than Parrakarry's method.

Parrakarry · 09-16-2004, 01:22 PM

Blah. Equation, algorithm.

Dark Magus · 09-16-2004, 09:07 PM

Quote:

Originally posted by Sidestream Dux:
Dunno, but there's still "Calculator" on the Start Menu. Are you not using Windows or something?

Good luck bringing your Start Menu to school with you.

09-14-2004, 08:18 PM	#1
The Cat OMGF! FUNNAY BAND RANK!!!!! Join Date: Jun 2000 Location: Yoshi\'s Island Posts: 5,213 Thanks: 0 Thanked 0 Times in 0 Posts Points: 2,170.00 Bank: 500.00 Total Points: 2,670.00 Donate	Do any of you guys know how to find the square root of any number without using a calculator?

09-15-2004, 10:15 PM	#3
The Cat OMGF! FUNNAY BAND RANK!!!!! Join Date: Jun 2000 Location: Yoshi\'s Island Posts: 5,213 Thanks: 0 Thanked 0 Times in 0 Posts Points: 2,170.00 Bank: 500.00 Total Points: 2,670.00 Donate	K, thanks, because my calculator broke. Still, I don't the idea of using trial and error to find a square root, but I guess it's the only method that works.

09-15-2004, 10:26 PM	#4
Parrakarry Veteran Member Join Date: Apr 2001 Posts: 10,684 Thanks: 0 Thanked 0 Times in 0 Posts Points: 9,810.87 Bank: 634.12 Total Points: 10,444.99 Donate	Ahh, but it's NOT trial and error. That's the exact equation your calculator performs to do a square root, too. Just a lot harder. XD

09-15-2004, 11:10 PM	#5
dux_is_me Member Join Date: May 2004 Location: Playing Many Marios at the NC forum Gender: Posts: 1,039 Thanks: 30 Thanked 26 Times in 14 Posts Points: 1,975.21 Bank: 22,475.83 Total Points: 24,451.04 Donate	Dunno, but there's still "Calculator" on the Start Menu. Are you not using Windows or something?

09-16-2004, 01:34 AM	#6
UserGoogol Senior Member Join Date: May 2000 Location: Greater Boston Area Gender: Posts: 4,024 Thanks: 0 Thanked 0 Times in 0 Posts Points: 5,380.00 Bank: 500.00 Total Points: 5,880.00 Donate	It's not an equation, it's an algorithm. Hmnm, but I'm not sure if calculators and computers use that method. There's probably a faster method than your algorithm. There's a long-division-esque algorithm explained here and elsewhere. It's much easier on humans than Parrakarry's method.

09-16-2004, 01:22 PM	#7
Parrakarry Veteran Member Join Date: Apr 2001 Posts: 10,684 Thanks: 0 Thanked 0 Times in 0 Posts Points: 9,810.87 Bank: 634.12 Total Points: 10,444.99 Donate	Blah. Equation, algorithm.