What is the probability of guessing (matching) a Guid?

Question

Just curious but what is the probability of matching a Guid?

Say a Guid from SQL server: 5AC7E650-CFC3-4534-803C-E7E5BBE29B3D

is it a factorial?: (36*32)! =

Answer 1

The number of possible GUIDs (128-bit value) is 2^128 or 3.4×10^38 — roughly 2 trillion per cubic millimeter of the entire volume of the Earth.

In other words, kind of low.

(Source for Earth volume reference: WikiPedia)