A dozen years ago or so there was a huge uproar about "common core" mathematics, which was a new standard being used in the USA for teaching.

It was a politicized trendy topic and even so-called-intellectuals were jumping on the train and calling it a deranged way of learning math.

I looked into it a bit, and I swear this pic pretty much sums up one of the key methods they were teaching.

Basically just tricks that a lot of people figure out to simplify problems.