Random number generators (RNGs) work by starting with a seed number and performing a different mathematical problem on that number every time a new random number needs to be generated. The seed number can often be over 200,000 digits long, and can change every second, making hacking extremely difficult, if not impossible. Third-party organisations have to inspect and approve RNGs in order to ensure that the programs and algorithms are fair and legitimate. In the EU, this is the Gambling Commission, whilst in the US, the authority varies by state, but in all cases, they ensure that they meet a variety of criteria.”]
Source: https://hackercombat.com/how-do-random-number-generators-work/