Some of us find it very difficult to count to two hundred. Counting to fifty is fine, then a person reaches seventy nine, and all hell breaks loose, because there is some evil demon that lurks some where between seventy six and eighty one, which reaches into the brain and floors the concentration.
I can count in twos until around twenty four, and I'd give myself a B-plus at counting in fives. Others of course can count comfortably in threes and in sixes. Which could be a blessing, but I have to say that I am truly suspicious of anyone who can manage it, and then smile as though it were a simple thing to do.