The most often asked question about newspaper columns is, "Where do you come up with this stuff?"

Today, the answer is simple. I mentally composed this while walking through a supermarket.

I’ve always had a fascination with grocery stores. I guess that has something to do with the fact that I like to eat.

My dad’s older cousin, Clyde, was a traveling macaroni salesman. When I was a boy, I went with Clyde to the grocery store and he told me all about the competition for shelf space, especially what is placed at eye level.

He also told me about end caps, those special displays at the end of the aisles. There are gurus who study the shopping habits of people and adjust the stores to maximize your purchasing. There are reasons that the produce aisle is in a certain place and the meat department is at the back of the store.

One of the things Clyde gave me was a price stamp. Long before there were bar codes, a group of people wearing aprons would stamp the price on the package with a purple ink that wouldn’t rub off. Clyde also gave me a small supply of the ink. I had to clean my hands with mineral spirits to get that stuff off.

After the price stamp was retired, along came the labeling machine. It would print the price on an adhesive label that was affixed to the package.

Now, the whole world revolves around barcodes. There are barcodes on everything. Even your tax return now has a barcode on it.

But things get moved around on grocery store shelves. If you’re looking for the lima beans in the 12-ounce can that are on sale, you have to make sure you get the ones with the right barcode.

Big food manufacturers are conscious of how much stuff costs. When diesel fuel was in the $5-a-gallon range, manufacturers were paying more to get stuff to the marketplace and prices went up.

Then, some mental giant had an epiphany: Let’s charge the same price and make the package smaller.

Have you tried to buy a half-gallon of ice cream lately? Those nice little tubs don’t hold a half-gallon anymore.

First, the ice cream folks went from a half-gallon (64 ounces) to 1.75 quarts (56 ounces). More recently, they have dropped to 1.5 quarts (48 ounces). They must think we can’t see that the tub is noticeably smaller. I picked up one the other day and it had this great information: Now contains 25 percent fewer calories.

OK, if you cut the container by 25 percent, you reduce the calorie count by 25 percent. But the price is the same as what you once paid for a half-gallon.

The same thing is true in cereal packages. I’m no rocket scientist, but my math skills are good enough for me to know that 12 ounces is less than 16.

At the rate they’re going, in a few years we can go to the store and buy a box with just the scent of what we wanted.

Do big companies think we are just plain stupid?