Plz tell me the method by following which we can find square root of num wihout using calculator,?

The only way is guess and check, there is no actual mathematical way without a calculator. So what you have to do is just do is do multiplication and play with numbers until you get really close. But you will never get exact because the square root of 3 and 5 are irrational numbers therefor they go on and on without repeating. So it would take quite a while to figure out the exact number.