Yes, all you use is 20, but as the number increases the odds of you finding your 20 goes up. I'm saying in 100,000 roughly randomly selected people, I have basically a 100% chance of finding my 20. 50,000 is probably enough.

By the way, if your number is not the same as mine, I am not intimating that this makes you deficient in some way. Everyone has their own number.