Hexadecimal floating-point literals

I've been programming in Java for more than 10 years, so I thought I knew the language inside out, but I just discovered a new, obscure feature: you can write floating-point constants in hexadecimal.

You can for example write: 0x50.1p3 which is equal to 640.5.

I never knew that, but it's in the Java™ Language Specification that you can use p/P as an exponent indicator.

Yeah, I never actually understood this one... I suppose some day it could come in handy?