Easiest way is to weigh 10 flat spoonfuls out, then do the division. If your scale can hold 10 teaspoons (5ml each) -- assuming you have a huge amount of MDHT -- dump all of that on. This divide by 80, and you'll be very accurate in your estimate of what each flat 1/8th tsp amounts to.
... after typing this out and looking up, I see that this pretty much says the same thing as Greenguy said... oh well, I typed it, so I'm posting it.