So I am a little ashamed that I have to ask this but here goes anyways.

I for the life of me cannot remember how to calculate this. Let's say we are cruising around at FL290 and we get a descent down to 5,000 feet. Local altimeter is 30.50 and we forget to set it (it is left at 29.92). We level off at 5,000 feet, what is our TRUE altitude? To me this seems like a low (29.92) to high (30.50) so we would be 580 feet higher than we should be. That is if we reset our altimeter correctly, it would show 5,580 feet. Am I doing this bass ackwards?

Thanks,
Ashamed CFI