Question

Which of the following are squares of odd numbers?
(1) 961​

Answer 1

Given:

• A number is given to us .

To Check:

• Whether it is square of odd number or not

Check:

Method 1:

First have a look at this table :

$\begin{tabular}{c|1}Unit\:Digit&Unit\:Digit\:after\:squaring \\\cline{1-2} 0&0\\1&1\\2&4\\3&9\\4&6\\5&5\\6&6\\7&9\\8&4\\9&1\end{tabular}$

Now its clear that if the units digit is a odd number then the units digit after squaring is also a odd number .

So ,we are given with 961 which has its units digit as 1 ,which is odd number .

Hence we can conclude that it is square of a odd number.

Method 2:

Also this can also be found by taking out prime Factorisation of a given number .

Now 961 can be written as 31×31 .

So , √961 = √31×31 = 31 ,which is a odd number.