Hello students, I am Dr Gajendra Purohit and you're watching my youtube channel where I upload videos on engineering, BSc and mathematics student if you're preparing for a competitive exam where higher mathematics is asked then my channel could be really helpful I've started a new series on CSIR NET where i'll be solving previous year questions Today i'll be discussing questions on number system whenever such question is asked take the middle number of the given two numbers that is 983716 now we can also write ultimately this will be equal to its product now we add 9 to the product we get a perfect square a two digit number can be written as 10x+y to calculate the unit digit y we solve this for such ques it is better to use the options after discarding the two options we need to check the other two we can see the correct option is D now there must be different values for this questions but looking at the options we know that the values are smaller A number that is closest to its square root the total sum of the angles is 180 and out of the 3 prime number it is important to have one even prime number i.e. 2 now we check from the options now 119 degree is div by 17 lets take b=2 which is the least prime number we'll type each number on a page the numbers from 100 will have 3 digit lets calculate and keep these two aside as from 100 - 999 will all be 3 digits subtract 189 from 2019 now for the number of pages we divide 1830 with 3 to 610 add 99 pages from before this is divisible by 3 121 id divisible by 11 10201 is the square of 101 you need to answer this question in the comment box below you need comment the correct option and the time you took to solve this question comment if this series is helpful or no you can my videos general aptitude on CSIR NET subscribe my new channel here follow me on instagram here comment down the answer to this question So Thanks a lot and B-bye!