Inspiration for this came from a recent reddit post that showed X% of Y is equivalent to Y% of X.

Full transparency, I am adult with kids and I never knew this equivalency was a thing – which is truly embarrasing and frustrating at the same time! I don’t recall this even being taught in my elementary school? Needless to say, I’ve gone all these years without having that helpful trick, and I don’t want my kids going through the same experience.

With that in mind, I’m curious about what other really useful math tricks/techniques each of you found helpful growing up. Focus here is basic math (e.g. mental math, quick on the spot calculations, simplifications of hard topics, transformations, etc.)

Key thing – just looking for basic concepts, not advanced ones.

Hopefully a quick change of pace from the crazy stuff I see all you posting about. FYI – love the sub, even if most of it goes whooshing over my head.

Thanks in advance (father of two young sponges)