Post History

(I’m going to do this post in pounds so that I don’t have to escape dollar signs everywhere. But the currency doesn’t matter.)

“Per cent” is, literally, “for each hundred”. Imagine making a literal pile of money from the cost of the item, and splitting it up into stacks of £100. So if the item costs £500, you have five stacks.

Now, a discount that’s “ten pounds” means just that: take £10 out of the pile (any stack, it doesn’t matter) and put it back in your wallet.

But “ten per cent” means £10 out of *every single one* of those stacks. For five stacks, that’s £50 I get to keep! I’d rather have that discount.

What if the price is only £100, though? In that case, there’s only one stack, and “£10 from one stack” and “£10 from every stack” mean the same thing.

*Below* £100, the intuition is a little bit trickier, because you have to imagine the 10% case as taking “part of” £10 from a stack that’s “part of” £100. But it’s not an insurmountable hurdle to envision that, and grasp that it won’t be as good as taking out a full £10.