system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: What exactly was the danger of the Y2K bug - what are the consequences of a computer recognizing '2000' as '1900'?
gpt
The consequences are that a calculation involving the difference between two dates suddenly returns nonsense values.

Imagine you're running a system that pays a pension for people aged 65 or over. Someone born in 1930 might have been quite happily claiming their pension as a 69 year old in 1999, but in 2000 the computer would think that they weren't even going to be born for another 30 years!