Aptitude - Square Root and Cube Root - Discussion
Discussion Forum : Square Root and Cube Root - General Questions (Q.No. 4)
4.
1.5625 = ?
Answer: Option
Explanation:
1|1.5625( 1.25
|1
|-------
22| 56
| 44
|-------
245| 1225
| 1225
|-------
| X
|-------
1.5625 = 1.25.
Discussion:
62 comments Page 4 of 7.
Priya said:
1 decade ago
We can write 1.5625 as 15625/10000.
So, (125)^2=15625 and (100)^2=10000.
So, by taking square root of this it became 125/100 So the answer is 1.25.
So, (125)^2=15625 and (100)^2=10000.
So, by taking square root of this it became 125/100 So the answer is 1.25.
Oshin said:
1 decade ago
Ya its 1.25, one method is.
Take last 2 digits 25, and square root of it is 5.
And 156 = 12*13, we must take smaller number, 12.
So its 125 and add decimal, then its 1.25.
Take last 2 digits 25, and square root of it is 5.
And 156 = 12*13, we must take smaller number, 12.
So its 125 and add decimal, then its 1.25.
Sai prasanna said:
1 decade ago
We can easily calculate by given options i.e.,
1.25 * 1.25 = 1.5625.
1.25 * 1.25 = 1.5625.
Vivek Wadhawan said:
1 decade ago
@Dipankar.
Your trick is good but didn't work for square of n. O whose digit ends with 7.
Let me give an example.
77^2 = 5929. That means acc to your trick sqrt of 5929 should be 73. Where it fails.
Another ex :- 27^2.
Your trick is good but didn't work for square of n. O whose digit ends with 7.
Let me give an example.
77^2 = 5929. That means acc to your trick sqrt of 5929 should be 73. Where it fails.
Another ex :- 27^2.
Amisha said:
1 decade ago
sqrt(15625/10000)
Now for 15625, separate into 156 and 25.
For 156, divide into two consecutive number i.e 12*13 and choose least number i.e. "12".
For 25, square root is "5".
Now combine both i.e. 12 and 5 which makes "125".
Now, 125/100 gives 1.25.
This is true for any which can fulfill the criteria i.e.
1. Consecutive number and choosing lower of both.
2. Last 2 digits 25.
This method is best when you know that the number is a perfect square.
Now for 15625, separate into 156 and 25.
For 156, divide into two consecutive number i.e 12*13 and choose least number i.e. "12".
For 25, square root is "5".
Now combine both i.e. 12 and 5 which makes "125".
Now, 125/100 gives 1.25.
This is true for any which can fulfill the criteria i.e.
1. Consecutive number and choosing lower of both.
2. Last 2 digits 25.
This method is best when you know that the number is a perfect square.
Raj said:
1 decade ago
Can you explain in more simpler manner?
Parthkushte said:
1 decade ago
Whenever a sq.rt. ends with "25"(1.56'25'), the last digit of root is always "5"(1.25).
The other 'digits can be found by this method: '12'X'13' = '156('1.56'25).
The other 'digits can be found by this method: '12'X'13' = '156('1.56'25).
Rakshit said:
1 decade ago
In main solution there is 225 instead of 245 might be.
Anil said:
1 decade ago
Can any one tell why 22 and 245 came in solution they give in the explanation?
Prashant said:
1 decade ago
1.25
---------------
1*1| 1.5625
+1| 1
----------------
22*2|056
+2|044
|-
----------------
245*5|1225
1225
--------------
0000
So answer is 1.25.
So that is the region, why we take 22 and 245.
---------------
1*1| 1.5625
+1| 1
----------------
22*2|056
+2|044
|-
----------------
245*5|1225
1225
--------------
0000
So answer is 1.25.
So that is the region, why we take 22 and 245.
Post your comments here:
Quick links
Quantitative Aptitude
Verbal (English)
Reasoning
Programming
Interview
Placement Papers