1. Ariane 5 (1996) — The European rocket exploded 37 seconds after liftoff due to an attempt to convert a floating-point number to a 16-bit integer. The program was simply copied from the previous model of the rocket, without adapting it to the new one. Price — 370 million dollars. Conclusion: code is not universal, even if you really want it to be.

2. Mariner 1 (1962) — NASA lost a space probe due to a missing hyphen in a formula that was copied manually from technical documentation. Without a hyphen, the formula told the probe navigation to “panic”, and the probe was shot down 293 seconds into the flight. One hyphen cost $18 million. Conclusion: the bug may not be in the code, but in the source code.

3. Therac-25 (1985–1987) — a medical accelerator irradiated patients with a huge dose of radiation due to a race between the flows and the lack of hardware protection. The device did not return errors — it thought everything was fine. At least six people died. Conclusion: trusting only software is dangerous. Especially if it is responsible for life.

4. Knight Capital (2012) — a trading algorithm in which they forgot to disable an old module, made thousands of trades in 45 minutes and destroyed $1.2 billion. The company survived only thanks to an emergency merger. Conclusion: tech debt likes to return at the most unexpected moment — especially in production.

5. Y2K (2000) — a bug that everyone was waiting for, but no one really understood. Old systems recorded the year as two digits (99 instead of 1999), and the onset of 00 was perceived as 1900. They were afraid of the collapse of everything — from banks to power plants. Bottom line: No disaster, but billions spent on emergency fixes. Conclusion: Even a “minor memory optimization” could become a bomb in 30 years.