 In this question, if you see we have been given to evaluate using identities and we have to evaluate the value of this particular arithmetic operation, right? So, the important thing is we have to use identities. So what was an algebraic identity? If you remember, there were lots of identities we have discussed so far. So, which one should we use here? So, is it in A plus B whole square form? A minus B whole square form? So, which one? So, the catch is if you look closely, the two numbers 1, 0, 3 and 97 are very close to 100, isn't it? So, 1, 0, 3 is 100 plus 3 and if you see 97 can be written as 100 minus 3. Beautiful, isn't it? So, if you see 100 plus 3 and 100 minus 3. So, if you look closely, it's again like this is A and this one looks like B. Then again this is A and this one looks like B and if you remember friends A minus B or sorry A plus B times A minus B was given as A square minus B square. This was one of the algebraic identities which we discussed before. So, very good looks like we can reduce this form, this particular expression in form of A square minus B square. So, A was 100. So, it will become 100 square and B was 3 over here. So, it will be 3 square, isn't it? Now, it becomes very easy to calculate why? 100 square, no brainer, you can put 4 zeros after 1, it becomes 100 square and 3 square is 9. So, now it becomes very easy to subtract. So, if you see using algebraic identities, we could reduce a multiplication, very ugly looking multiplication in fact into a very sweet subtraction problem. So, you can figure out the answer. So, it's nothing but 1, 9, 9, 9. Is it? So, answer is 9991 very easily done using identities. Let us take another one to reinforce the learning. Okay, here is another question. So, question is evaluate using identities. Again, what kind of identities we are talking about algebraic identities? There are trigonometric identities, other identities as well. Okay, so how to evaluate using identities? So, that means 0.99 square. So, now 0.99 square could have been calculated by our usual multiplication method, isn't it? But then that would be a cumbersome process. Then what is the use of learning algebra? So, hence let us see how algebra rescues us from this cumbersome, this ugly looking multiplication problem. So, if you see 0.99 is nothing but 1 minus 0.01, isn't it? 0.99 is 1 minus 0.01 and there's a square. So, now if you consider 1 as a and let's say this 0.01 as b, then this is simply a minus b whole square, isn't it? And from our knowledge of algebraic identities, we know a minus b whole square is a square minus twice a times b. These dots are not decimals, these are multiplication. So, a square minus 2 times a times b plus b square, this is an algebraic identity. So, let us use this. So, where a is 1 and b is 0.01, so a minus b whole square will be nothing but 0.99 whole square. And using the identities, I can write this as 1 square minus 2 times 1 times 0.01 plus 0.01 whole square, isn't it? So, if you see this is nothing but 1 minus 0.02 plus 0.0001. I hope you know how to square a decimal number. So, there are 2 digits after the decimal. So, if you square it, there will be 4 digits after the decimal. So, if you see this is the value. So, hence, if you really solve it, it is 1.0001 minus 0.02, which is nothing but if you do the calculation, this is 1, 0, 8, 9 and 0.9801. You can do this on the sidelines as well. So, 1.0001c and then I have to subtract 0.02 from here. So, you know this is 00. So, 1 minus 0 is 1, 0 minus 0 is 0, then 0 minus 2. So, hence, you have to borrow. So, it is 10 minus 2, that is 8. So, this 0 becomes 9 now. So, 9 minus 0 is 9. And since you borrowed, so nothing is left here. So, it is nothing but 0.9801. So, this is the answer to this particular problem. So, hence, we learnt what using an identity to solve a mathematical arithmetic problem.