system
Given the following post, respond as if you're commenting on Reddit:
human
[WH 40K] Size and Statistics of the Imperium of Man?

So I know the IoM controls at the very least 1 million worlds however i've read elsewhere that 1 million worlds is only stated ato give a satisfactory answer to the question, as no one has any idea how big the IoM has expanded to become. I've heard from anything between 1.5million worlds to as many as 10 million inhabited worlds. Also would like to know size of the Iom Army and Navy.

Bonus question: How many Orks are in the galaxy and how many worlds do they inhabit?
gpt
Statistic of the Imperium of man is impossible.

Some high worlds are so full of people that the governors sometimes perform culling to keep the population under manageable size.

Not to talk about it's impossible to count the people of a Hive World, many of them have never even heard of the sun. By the time you counted all of them 3 generations would have passed and you must start again.

No one probably knows exactly how many worlds there is in the Imperium, they are after all constantly loosing and gaining worlds. As long as every world have been ordered a tith and said tith have been send to an other worlds to be made in to supplies for factories, the Imperium does not care.

And finally, no one knows how many men and women serve in the Imperial Guard Astra Militarum. It is so many new recruits all the time and so many death at all time that it's impossible to keep track of it all. Even keeping check on the number of regiments is considered hard, the Administratum had to create a special wing, the Departmento Munitorum to keep the Imperial Guard stocked with all the supplies, vehicles, ammunition and weapon needed.

About the Orcs: Far to many, if the Orcs were to unite as a single force (that thankfully would never happen), they would wreck and destroy every other faction in the galaxy.