title: Mathematica: exporting to a variable path
body: <p>this is tricky.
  Once the path to export data in Mathematica is under quotes, how can I insert a variable as part of the path? In other words, I'm inside a loop that increments VAL and want to export MyData to VAL.dat. Ideas? </p>
  
  <p>Pseudocode:
  Export["~/Documents/VAL", MyData]</p>