A brain teaser featuring a four-digit code has been puzzling Twitter users. While many suggest the code is 3841, but some argue it could be 4891. Monday, Jul 14, 2025 ...

A brain teaser was shared on Instagram’s Threads, and it has left people boggled. The mind-bending brain teaser asks people to guess the 3-digit code of a lock based on a few hints.

#186 Neural network. Set by Peter Rowlett. Professor Beryl Brainstein is developing a robot called NewRon that uses a so-called neural network to crack open a safe that has a four-digit code.

Video There's nothing particularly difficult about cracking a smartphone's four-digit PIN code. All it takes is a pair of thumbs and enough persistence to try all 10,000 combinations. But hackers ...