title: Formula to find square root of a natural number using only addition and subtraction
body: <p>How to use only addition and subtraction to find out square root of a natural number?<br>
  Thanks.<br>
  [I have looked over the internet but i didn't find any content related to this problem.]<br>
  <strong>Explanation to my problem</strong>: I want to create a c function which will receive only a natural number and return square root of it.<br>
  <strong>You may say to use the "sqrt" function</strong> but i just thought of creating one which will utilize addition and subtraction operator to create the square root.<br>
  <strong>You don't have to write the program, just writing the formula for it will be just fine. Thanks.</strong><br></p>
  
  <p><strong>Update: This question is not specifically about coding rather about mathematics.(I tagged "c" as it had some link but this question is NOT about coding.)</strong></p>