We were discussing the cost of our cat. He's 17.

I said, ok, 300 days/year x 20 years is 6000, if we spent

$0.50 per day, that's 3 grand.

My wife disagreed, so I fired up calc and did the exact

math, 365 x 17 x 0.50. That gave 3102.5, which is within

4%

As an engineer, I am able to do very quick "back of the envelope" calculations.

The $250 vet treatment he once had is a mere 8% of total cost (not included in above). Since he doesn't use a litter box, we save. Since he has peed on clothes, there are extra washing costs. Since cat food is probably more than $0.50 a day, the actual costs are probably higher. Once we paid a neighbor-kid to take care of him during a vacation, too. Small change compared to cumulative maintenance (food).

He is, of course, worth it.

At ca. 10 lbs, that is $300/lb, or about $19/gram. That's about $1/gram/year.

Oh yeah, he was spayed when he started marking inside a neighbor's apartment. I got him for free though.