Efficiency - someone double check my numbers?

Math is not my strong suit but I can hold my own. None the less I'm a bit skeptical of how I'm figuring this. This is only my second time AG and if I am actually right I managed to pull off an 84.88% efficiency using this method: "How to Brew" Efficiency Calculation

Here's my grain bill/numbers:

8.75 lbs Maris Otter (38 max Ppg)
0.66 lbs white wheat (37 max Ppg)
0.50 lbs Crystal 60L (34 max Ppg)

Preboil Gravity: 1.049
Preboil Volume: 6.5 Gallons

It doesn't figure into the calculation but I mashed 90 minutes at right around a 1.6 q/# and overshot my temps with an average mash temp of 157. First runnings were 1.077 with final runnings 1.031. They were running pretty clear by the time I finished.

Thanks for the help/suggestions...

Your efficiency calculations are correct assuming your pre-boil gravity was correct.

Ok.. thanks...

Yeah, read the pre-boil gravity after I had cooled the sample to 62.8F and accounted for correction. Guess I can't argue with the efficiency I ended up with. Pretty shocked really...