title: Assign integer value to letter
body: <p>So i have this problem. I have Text Box with text containing 12 numbers. So for example 012345678912. Now i don't know how to assign the first, then the second .... and so on numbers to letters like a,b,c,d,e,f,g,h,i,j,k,l because i need them to calculate the 13th (m) number with the following formula</p>
  
  <pre><code>m = 11 − (( 7*(a+g) + 6*(b+h) + 5*(c+i) + 4*(d+j) + 3*(e+k) + 2*(f+l) ) mod 11)
  </code></pre>
  
  <p>Also i tried to make this formula in to c# readable text and i got this, hope it is correct</p>
  
  <pre><code>int result = (int)new DataTable().Compute(" 11 − (( 7*(a+g) + 6*(b+h) + 5*(c+i) + 4*(d+j) + 3*(e+k) + 2*(f+l) ) mod 11)", null);
  </code></pre>