Nested IF Statements

The code that you posted has a few problems that would prevent it from running. 

if(Condition=='Item2,'2')

You're missing the closing " ' " at the end of " 'Item2 ". 

Additionally, you're starting the "if" using the lowercase "i" which isn't the NintexRuntime Function way of expressing that. 

Also because you're closing off the statement prematurely with an ending parens ")", there is no 'else' argument so it couldn't actually execute the statement after this one. 

If you wanted to use the provided Nintex Runtime Functions then you'd need to write it out as is follows: 

If(Condition ==='Item1',1, If(Condition === 'Item2', 2, If(Condition === 'Item3', 3, If(Condition === 'Item4',4, If(Condition === 'Item5',5,0)))))

As you can see, it's just a long chain of Ifs and Elses, and at the very end if nothing is true, then we simply return 0. 
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I personally hate how this looks, and you'll need to remember that EACH time you see the word "Condition" that is a Reference that you must insert pointing to the Form Control. 

Another way of doing this would be to write it out as more of a pure Javascript way. This is how I'd probably write it in most cases:

// A more easily readable and expandable version that requires fewer Control References
(function(conditionValue){
  var valueMap = {
    "Item1": 1,
    "Item2": 2,
    "Item3": 3,
    "Item4": 4,
    "Item5": 5
  };

  return valueMap[conditionValue] || 0;
}(Condition))

This way, if I need to add in a new Option to the drop down, I'm only adding to the 'valueMap' object (don't forget your comma if you add a new property!), and anything outside of those properties will return a 0. 

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Here are a few shots of both these methods in action (Spoiler: they do the same thing): 

I hope that this helps you along your way! 

That's exactly what I needed - thank you, thank you, thank you!!!