I've noticed a lot of media outlets like to add a zero here and there when reporting.
A mix of 300 people could fill the IKEA parking lot. 3000 is an entire cruise ship.
You piqued my interest so I went to look it up. Average Ikea is 300k sf. So obviously omitting the fact that there are areas of the store that are off limits (although are you following those rules when you're playing hide and seek?), as well as there being furniture everywhere, that's 100 square feet per person, which I think is doable. Especially considering, if I'm playing hide and seek at IKEA, I'm hiding in the furniture.