Aptitude - Square Root and Cube Root - Discussion

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"Everything should be made as simple as possible, but not simpler."

- Albert Einstein

1.5625 = ?

[A].	1.05	[B].	1.25
[C].	1.45	[D].	1.55

Answer: Option B

Explanation:

   1|1.5625( 1.25
    |1
    |-------
  22| 56
    | 44
    |-------
 245| 1225
    | 1225
    |-------
    |    X
    |-------

1.5625 = 1.25.

Varun said: (Sat, Jul 24, 2010 10:15:16 AM)

We can write it as 15625/10000. 5 power of 6 is 15625 and it becomes 5 power of 6/10 power of 4.. 125/100=> 1.25

Abinash said: (Thu, Jul 29, 2010 11:50:07 AM)

Well I think in the 3rd step it should be something after 22 not 24..yes or no? if 245 then how?

Deepti said: (Sun, Aug 1, 2010 02:58:38 AM)

Varun's explanation is easier to under stand.

Rajesh said: (Thu, Dec 16, 2010 07:24:22 AM)

the power 6 and power 4 get cancel. then we have 5 power 3 and 10 power 2.

Sajitha said: (Wed, Dec 29, 2010 05:55:38 AM)

Varun your solution is very helpful.

Shri said: (Sun, Feb 27, 2011 12:47:01 AM)

Anyone can explain varun's 3rd step?

Sakshi said: (Wed, Mar 2, 2011 09:09:14 PM)

Hi Shri! 5 power of 6 and 10 power of 4 we can write it= 5 square5 square5 square/10 square10 square under root it will bcome 555/1010 =125/100 =1.25

Shalini said: (Fri, Jun 17, 2011 08:24:54 AM)

15625 we can distributed in two parts like 156/25 becouse we calculated the sqaure any number were ends digit is 5 the last digit of answer is always 5. now camo to second part of d no. square of 12 is 144and square of 13 is 169. square of 13 is > 156 so that we took 12 now we get "125" is the right ans.

Abhay said: (Fri, Jun 24, 2011 06:35:58 AM)

Sakshi...U r the Best!! Awesome... Thnks Too...good

Rakshit said: (Tue, Jul 26, 2011 01:03:10 AM)

@Sakshi is this method works for all numbers that has the last digit as 5 ?

Arun.G said: (Mon, Sep 5, 2011 12:27:28 PM)

I'm not understand the answer 1.25 according to me we divided 1.5625 the answers are 1, 22, 245 how 1.25 comes.

B.Sridhar said: (Sat, Oct 1, 2011 11:01:45 AM)

Shalini explanation is good but the number is different that is 17079 how to calculate please tell me.

Kiran said: (Thu, Oct 27, 2011 08:29:09 PM)

Varun explaination is very good.

Murali said: (Fri, Nov 25, 2011 12:41:01 AM)

root of 1.5625 = ? We can write it as 15625/10000. =1.5625 = root of 1.5625 = 1.25

Ranjeet said: (Sun, Jan 8, 2012 08:27:19 AM)

How instantly get 5 power of 6 = 15625 as explained by Varun initially, is there as short formula please explain any one ?