Diminishing marginal returns

[Tanya Shivari]

phenomenon in which greater input of effort, money, etc. yields smaller results. Crucial part of the idea is that if youre using x to get y results (where y is the thing you want). then additional input a will yield additional results b, but not in the same proportion as before.
On average, before, you put in x to get y, so your yield was y/x. But if you increase x by amount a, then your results will be y b, where
(y b)/(x a) < y/x
and this will only get worse.
[Diminishing marginal returns] ([DMR]) is used to explain why the supply curve in economics slopes upward, i.e., increasing the quantity supplied requires an increased price of most things.
Sometimes DMR is more than offset by [economies of scale], which allows more of a thing to be supplied more cheaply than a small amount.