Humans cannot consciously generate random numbers sequences. when making up numbers humans will often avoid two numbers in a row and will often pick the number 7 and start with a 1 so in order to pick a number that has the least chance of being picked by someone else on the spot you should avoid these pitfalls. if you have the time generate a random sequence for example  606533uw these values are generated randomly in the pattern (\d){6}([a-z]){2} as in 6 random digits and 2 random letters. it does not start with a one and does not contain a 7 so the chance someone randomly picks it is very small.
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