Never Tick Off an Engineer

I received this picture in an email. I receive engineering jokes all the time and I not sure if others find them as amusing as I do, but I think this is hilarious.

Sorry I tried to enlarge the image, but it came out too blury. Hope everyone can see it.

By the way, no I did not figure what is the amount. It would not be as funny. Besides my brain hurts anymore, when I try to do simple calculations!!