title: Determining Length of Double Type Variable in C
body: <p>I am using the following code to come up with a number. </p>
  
  <pre><code>NSString *userNameOne = txtUserName.text;
  double numOne = [userNameOne intValue];
  
  double agedecade = numOne/10;
  double betaage = 0.23260;
  double meanage = 5.64301;
  double one_age = agedecade - meanage;
  double age_final_var =  one_age * betaage;
  </code></pre>
  
  <p>If the user input 55 into the <code>numOne</code> variable, the answer will be -.033264 using the above program.</p>
  
  <p>However, if I do the same on a calculator I get -.033264126. I would like to get the extra three digits into my program. How do I get the missing three digits (...126) into my program above? </p>
  
  <p>**
  I happen to be using this code in an iPhone App, saying this in case this changes things.</p>