[tiagod]

High aperture = Blur

Unfortunately the lower number actually means bigger aperture.

[sneela]

And that's what exactly confused me :)

With my mnemonic, I say low *number = blur

I should have been more specific

[Filligree]

The aperture size is usually described as e.g. f/32, where f is a camera-specific constant.

Denominator, not numerator. That's why larger number = smaller aperture.