Generally if you see "NaN" in one of the result fields on the front end you have a problem with your formula. The most common problem is you're trying to use a result from one result set in a second or third calculation and one of them isn't an integer or float.

Here's a common example:

Let's say your calculating the cost of Apples which happen to be $0.99 each and the tax rate of 10% on those Apples based on the number the user inputs.

filed1 is the number of apples.

result1 is the number of apples times the cost: (field1*0.99) and the output is currency.

Result two is the total of result1 times the tax rate and the output is currency. The formula would need to be ((field1*0.99)*0.10).

If you tried to use (result1*0.10) the output would show NaN because it isn't capable of using results from another set that output is set to currency.

The ability to use result1, result2 and result3 within a formula is very limited due to the calculation script. It just gets confused with it tries to calculate when currency symbols get involved.