Question

which of the following is the most likely order of magnitude for the population of the large U.S. city, Such as New york city

Answer 1

Would it be 10, 6, 4 or 8

Answer 2

Google says New York City's population was 8.245 million in 2011. That's like 8,245,000.

To find the order of the that, take its log!

I got ~6.916. That's about 7!

But many other large cities have numbers slightly under one million. Like 4,000,000.

It has a popup, but also numbers:
http://www.infoplease.com/ipa/A0763098.html

That's about a 6 and a half for the bigger cities.