Calculating exact gravity of Weizenbock

[Roobiedoobiedoo]

I just finished brewing a weizenbock. I took a gravity reading before I had it topped up to a full 1 gallon so I was wondering if anyone could help me calculate my actual OG. I got a hydrometer reading of 1.100 @ 65F in 0.875 gallons of wort. I added 2 cups of water at 65F to being it up to a full gallon. Anyone better at math than me wanna take a crack at this?

 

[Roobiedoobiedoo]

So I'm still not sure what the OG calculates out to, but I'm estimating around 1.085-1.095. Fermentation's off and running. I woke up the morning after and the cup of sanitizer I have the blow off tube in was full of foam. Dumped that and switch out a new sanitizer cup. I'll post results and FG when it's done.

 

[Roobiedoobiedoo]

Take your first gravity reading (only use the last two figures) and multiply it by your volume. Take that total and then divide it by your post top off volume. Example - 1.060 or 60 x 5 = 300. 300 / 6 = 50 or 1.050.

Using this formula I get an OG of 1.0875, round up to 1.088