# Total Correct Yields Only Undefined

I am trying to compute the total slides that are correct in this activity on slide 13. The result is always undefined. What did I do wrong? Help.

So, I think the reason actually for the NAN error is that you have an extra â€ś+â€ť at the end of your summation statement on slide 13. Taking that out eliminates the errorâ€¦ butâ€¦

I still donâ€™t think this is going to work the way you intend. Your statements correct = 1 are going to contribute 1 to the tally no matter the correctness of the screen. You want to tally a +1 only IF the screen is correct, but correct = 1 is giving a variable â€ścorrectâ€ť the value 1, it is not checking against the correctness check.

So I just played around a little bit, and there is probably a better way, lolâ€¦ but this ought to work.

In the component, for example the first math input, I put:

check1 = c1graph.number(â€śI_câ€ť) = 1

correct: check1

sum1 = when check1 1 otherwise 0

So check1 is the test for correctness, and then the correct sink will be true if check1 is true and 0 otherwise. (I always prefer to do correctness checks this way - in a separate variable - because then that script can be called wherever needed.) So then you can also USE the script check1 to â€śtallyâ€ť the score in the variable sum1.

Now in the note on screen 13, I used:
total = numericValue("{c1input.script.sum1}+{c2table.script.sum2}")

(I only fiddled with the first 2 screens, but you get the idea, and I was able to test it and it seems to work - no NAN error.)

You are amazing! Thank you for your help!

1 Like