There are number of tricks to find square of any 2 digit number so have a look at some of them.
Trick No. 1 :- Let me explain the rule of finding square of any 2 digit number with the help of some examples.
Example 1. Suppose we want to calculate square of 47.
Solution :- 472 = (47+3)*(47-3)+32
= (50*44)+9 = 2200+9 = 2209
In this method, we have to make a number ending with 0, that’s why; we add 3 to 47.
Example 2. Suppose we want to calculate square of 75.
Solution :- 752 = (75+5)(75-5)+52
= (80*70)+25 = 5600+25 =5625
Similarly , we added 5 to 75.
Comment below in case you find any problem in this technique.
Trick No. 2 :- We all know how to calculate square of any number by regular method. That is if we want to calculate for 99 then we will multiply both the numbers and get the result as 9801. But regular method takes precisely more time than the method i am going to discuss here.
Lets understand this method with some examples :-
Example:- Find the square of 99
- In order to find the square of 99 we would select a number greater than 99 and is nearest to it. In this case that number is 100.
- Now we will subtract (2 x 99 x 1) +(1)2 from the square of selected number i.e., from 10000.
- The one in above line is from 100 – 99 here.
- Hence the equation will look like (100)2-[(2x99x1)+1].
- Which is equal to 10000 – 199 = 9801.
Hence the result is 9801.
Lets take one more example
Example:- Find the square of 87
- In order to find the square of 87 we would select a number greater than 87 and is nearest to it. In this case that number is 90.
- Now we will subtract (2 x 87 x 3) +(3)2 from the square of selected number i.e., from 10000.
- The 3 in above line is from 90 – 87 here.
- Hence the equation will look like (90)2-[(2x87x3)+9].
- Which is equal to 8100 – 531 = 7569.
Hence the result is 7569.
The above method is far better than the method we are using till date. So a little bit practice by using this method will save your time in competitive exams as compared to other students.
For squaring a number ending with 5 Click here ..!!
In case if there is any doubt in these method please let us know in the comment box below. We are happy to help you all.