My minimal backpack camping checklist has 25-50 items on it, and that's with counting "first aid kit" as one thing, "tent pegs" as one thing, not counting clothing I'm wearing, "food" as 1 item, etc.
There is no way that an adult has 100 things inside an entire flat they eat, work, leisure, and sleep in. I assume that they mean 100 valuable things that they wouldn't want to just lose.
You never know, some people go to extremes. One fork, one toothbrush, one sleeping bag, one laptop, one credit card, done. Toothbrush doubles as a shower brush and credit card is used to scrape off water instead of a towel.
Of course, the shower isn't yours so it doesn't count. Using this, we can get rid of the sleeping bag and just roll up the carpet in the rented flat and sleep in that.
There is no way that an adult has 100 things inside an entire flat they eat, work, leisure, and sleep in. I assume that they mean 100 valuable things that they wouldn't want to just lose.