I pretty much gave you the answer. Look at it. There are 1000 digits in the number. Therefore, counting off blocks of 3 from the far right of this huge number gives us 3,739,..................
So, the next number after the comma is 7.
You could even run it through a calculator. My TI-92 gives me
So, there are 999 digits after the 3 and the first one is 7.
BTW, do you use decimal points instead of commas in Europe or wherever?.
In the US, it's commas to separate the 1000's.
For instance, 1,000,000,000
Would you write 1.000.000.000?
If so, that's wacky and wrong. Do it the right way.