It's way less than thousands. To get this specific bug - one 'e' in the 7th digit and 9 digits less than 'a' - is 1/16*(10/16)^9 = 0.009095. Just under 1 in 10

It's way less than thousands. To get this specific bug - one 'e' in the 7th digit and 9 digits less than 'a' - is 1/16*(10/16)^9 = 0.009095. Just under 1 in 1000. But if the 'e' is in the 2nd,3rd,4th,5th,6th you'd get the same bug, so actually about 6 in 1000. But around 1% of the hashes will be all decimal digits and will parse as numbers ((10/16)^10 = 0.009). That's common enough that I've seen that one cause errors in our code too (somebody had code reading the hash then trying to append it to a string).