Hahaha, II love that you're kinda faking them out even if you're right or not lol. I used to work as a cashier, and I would always guess the weight of the vegetables/fruits before putting them on the scale/scanner thing because i love estimating that stuff too. I did it out loud once and got it almost exact and a couple customers jeard and wete impressed. So I tried a few times and the customers in line and I made a game of it and cheered or "awww"ed when I got it wrong. So fun.
I also like trying to guess the amount of something i need for recipes. Like, a recipe calls for a cup of onions, I look at the whole onions in store and based on size I imagine what it would look like diced in a measuring cup, I usually get close and its so satisfying
Oh man this is kinda similar to a quirk I had as a kid. It's kinda hard to explain, but in my old neighborhood we had sidewalks like these. So if you look at the first five rows of squares starring from the bottom of the picture, you'll see that the color of the cement changes on the next row. Well the sidewalks I walked on, there would be like, 3 or 4 rows of blocks with a thicker kinda borderline between eachother. So when I would walk I would step one foot in front of the other in each block and count "one two three four, one two, one two three, one two three" etc, starting the count over every time I crossed the break or change in the cement.