I feel like since they are mostly water weight, the math doesn't always look great. But let's go through it!

For example: https://www.walmart.com/ip/Russet-Potatoes-10-lb-Bag-Whole/10449951?classType=REGULAR&from=/search

10 pounds of food for $3 sounds great, but in a pound there is only 300 calories about, depending on type/peel/etc. So 3,000 calories for 3 dollars. At $1 per 1000 calories it isn't bad.

But let's compare to this 5 pound bag of flour for 2.38, at 3 cents an ounce:

https://www.walmart.com/search?q=flour

A pound of flour has 1,600 calories. So this bag of flour that is cheaper than the potatoes, has 8000 calories for 2.50. But you'll need to put in some elbow grease to make it edible. Doing a sourdough is probably the cheapest way to do it since all you need is flour, water, salt, and the starter you made using flour, but it is more time intensive. So about 3,200 calories for a dollar.

Rice comes in with a very similar amount of calories, but just a little more expensive at 4 cents an ounce:

https://www.walmart.com/ip/Great-Value-Long-Grain-Enriched-Rice-5-lbs/10315395?classType=REGULAR&athbdg=L1600&from=/search

Rice is a bit easier to turn edible though, so the extra dollar might be worth it for a 5 pound bag. 2,400 calories per dollar spent.

Then oatmeal comes in as our most expensive at 7 cents an ounce.

https://www.amazon.com/dp/B01KV4H51G?tag=sacapuntas9-20&linkCode=osi&th=1&psc=1

At once again 1600ish calories for a pound of dry oatmeal, it is 1.12 per pound. So it is creeping up closer to the price of potatoes TBH, and if you were super on a budget the oatmeal would be the first to go. But I suppose potatoes aren't "that" much worse than oatmeal. But my thought was oatmeal is good breakfast option so wanted to include it, and the top bit is mostly setup for bottom.

Knowing this stuff is helpful to our daily lives because rich people hate us.