Personally, I've found myself a few times unable to count. Not simply distracted or impeded by visual problems, but the very process of counting became "unstable". All those times were under the influence of Ayahuasca. It's difficult for me to describe what was going on as I cannot always induce the state so it's hard to do experiments. Basically, as I tried to count something, I just couldn't focus on quantity. You know how you can sometimes just "see" 3 objects to the point where you can count by 3's? Well, I sort of kept seeing 7 or 8 or 4 as I was trying to count one by one.

Anyway, I'd love to hear other accounts of people experience disruptions in their perception of quantity.

I can't really count while tripping, and the concept of numbers suddenly gets funny. Darn that uptight old left brain and its rigid categorization methodology!

I used to visit a float tank place in Chicago, and on the way out after altered sessions, I'd find myself completely confused at the cash register. Fortunately the owners were friends of mine.

Haha, this reminds me of a few times that I tried to read clocks and comprehend time while journeying! I remember thinking, "ok, you know how to tell time, you know how a clock works. Why on earth is this not computing?" It's the same with counting money. I don't know how many times I've counted and re-counted dollar bills, only to give up in frustration. Good times!

I've never had trouble with counting persay (but then again, I can't really remember trying to count anything anyway...I'll get back to you ) but there have been times on DMT when I've gone to whip out the ole phone to check the time or something to that extent and I just stare at the archaic numerals on my phone blankly.

Well, I certainly find myself unable to comprehend quantities of time when tripping.

I remember sitting in the back of a taxi coming up on a strong tab of LSD, and on arriving at the destination the driver turned round to me and quoted the price as displayed on the meter (which it was beyond my visual preceptive abilities to read).I pulled out a note and some change from my pocket, looked at it and had no idea of what I needed to do next.

The taxi driver waited what seemed like a while(!) then reached across and took what I presume was the required amount out of my outstretched palm and spoke to me in a soothing way, asking me to take care of myself.It was dark but I think my saucer-sized pupils and inability to speak probably gave me away.

So yes, correct appreciation of quantities and whichever part of the cerebrum is responsible for this, can certainly take a direct hit with psychedelics.

High school, tripping my brains out in Algebra class, confident I could just blend into the group and not be noticed. I'm staring at the graph paper styled grid that is etched into the blackboard, patterns dancing across the matrix. My teacher (a really great guy, one of the best teachers I ever had in all of schooling including college) is writing an equation on the board, formula for a parabola or such, and after reading it he says, "So the value of X is?" and calls my name...

I just collapsed in a fit of laughter and after a moment or so he moved on to the next student. I was an A student, so he gave me a break, I guess.

Actually, in my high school this was not even that extreme of a thing. A great many odder things happened there all the time.

I have never had a problem counting on psychedelics. Maybe a clock because I could not read it due to visuals. I think practice makes perfect. You need to go out and try new things on psychedelics all while staying safe. Go shopping why not the most someone is gonna think is that your crazy maybe. Always have a sitter to get you out if needed and drive for you. I use to pushed the limit's with LSD to see what type of situations and people I could handle. This challenges your perceptions of self that limit you and makes you realize what you can achieve. Even against what seems insurmountable odds I mean Jimmy Hendrix could get on stage and put on an awesome show when tripping. Music is mathematical and I understand it better when tripping. Don't let it put you in a stupor unless your trying to trance out.