title: NSArray multiply each argument
body: <p>Is the there a way to multiply each NSNumber contained in the array by 10?
  Here is what I have so far:</p>
  
  <pre><code>NSMutableArray *vertex = [NSMutableArray arrayWithCapacity:3];
  
  [vertex addObject:[NSNumber numberWithFloat:1.0]]; 
  [vertex addObject:[NSNumber numberWithFloat:2.0]];
  [vertex addObject:[NSNumber numberWithFloat:3.0]];
  
  [vertex makeObjectsPerformSelector:@selector(doSomethingToObject:)];
  </code></pre>
  
  <p>I am not sure what selector to use to do this, please help!</p>