Please make me understand about karl pearsons cofficient of correlation..

I have to learn how to construct correlation from all methods...???

Karl Pearson's coefficient of correlation is a mathematical measure of correlation. It is denoted by 'r' and calculated using the following formula.

Follow the below mentioned links to understand the Karl Pearson's coefficient of correlation method.
https://www.meritnation.com/ask-answer/question/how-can-we-derive-the-formula-of-karl-pearson-s-cefficient-o/correlation/3380421​
https://www.meritnation.com/ask-answer/question/how-to-calculate-the-step-deviation/correlation/6778023​