I got 38x with 117 billion total people. Not sure where OC got their number, but it's kind of in the ballpark, so maybe it was just shitty mental math.
The easiest way would be to say 117 billion is ~2^37 because 2^[7, 10, 20] are 128, 1024, and about a million (1024*1024), so multiplying those all together gives a little over 128 billion, which is pretty close to 117 billion. So, 242/237=2^5=32. Pretty close, all mental math. Granted, it does require you to either memorize or compute powers of 2 up to 10.
I had to check the math and I was surprised that 2^42 is “only” 4.4 trillion. Thought it would be a lot greater like there are less atoms in the universe similar to the uniqueness of a shuffled deck of cards.
I typically associate "clone" with "an exact copy", with the same exact molecular layout and even thoughts. So a literal exact copy. Clones on a DNA basis, so something possible for years, would indeed be different in some details.