Missed Metformin Dose

I forgot to take my metformin this morning at 7am! OMG! What shall I do?

Well, according to Wikipedia, the half life is between 4 to 8.7 hours. I assumed 6 hours. Thanks to a little googling, the formula to use is below. I modelled it based on taking my morning pill at 5pm when I got home and skipping my evening pill (which is not at 7pm, but usually around 9pm to 11pm), and:

The formula:

I like useful math