Squaring of a number ending with 5

After you read this article , you would be able to find the answers to the square of numbers ending with 5, almost instantly and mentally.
For example , you squares of 35 , 75 , 95 , 105 etc.
Here's how to do it,

Imagine in mind the number, suppose 35 in your mind to be of two parts "3" and "5" ( If it is difficult for you to imagine , write it at a piece of paper )
Now, multiply the first part of the number with a number that is one ( 1 ) greater than it ( Here, "3" is to be multiplied with "4" as 3 + 1 = 4 ) , this will be the first part of your final answer.
Here, 3 x 4 = 12 , so , 12 will be the first part of your final answer.
Next we know 5²=25 , so 25 will be the next part of your final answer.



SO, your final answer becomes 1225 .
Likewise,
95²= ( 9 x 10 becomes the first part, and 25 becomes the next part )
= ( 90 , 25 ) [In the above step "9" is multiplied with "10" since 9 + 1 = 10 ]
= 9025 [ Final answer ]

Taking another example,

105²= ( 10 x 11 becomes the first part, and 25 becomes the next part )
[ Note : The first part will always be the number(s) except 5 ]
So,
105²=( 110 becomes the first part, and 25 becomes the next part )
= 11025 [Final answer ]

Self-Exercies:-

a) 55²= ??
b) 65²= ??
c) 125²= ??
d) 205²= ??