Which of the following is a perfect square?
.	Choose the correct answer:
A) 649
B) 961
C) 1664
D) 2509
E) 100000
The best way would be to see the range in tens and solve after looking at the units digit   lets see all choices--   A. 649   20^2=400 and 30^2=900..   since only 3 and 7 have the perfect square ending in 9, we require to try only for 27 as it is more than 25^2, 625   it is not 27^2, as next square of 26 itself after 625 will be &gt;625+2*25,675   actually 26^2 will be 25^2+25+26   B. 961   between 30^2 and 40^2...   only 1 and 9 have squares ending with one..   since it is very close to 30^2, 900.. it can be 31^2   CORRECT   C. 1664   between 40^2 and 50^2..   closer is 42, but that should be atleast 1600+41+42.. NO   D. 2509   between 50^2 and 60^2..   very close to 50^2 so next square of 51 will be at least 2500+51.. no   E. 100000   odd number of 0s, not possible   ANSWER:961
<result>B</result>
Which of the following is a perfect square?
.