[iso1210]

5% sorry. It's a reasonable long term return.

25 years per generation.

Year 0: 10m Year 25: 33.8m. 3 kids, give them 10m each, leaving you with 3.8m for the rest of time

This repeats as long as you want.

Over 100 years at 5% you have 1.315 billion over 120 people, which is 10.95m each.

At 4% you'd have to have a 29 year generation, which is certainly more realistic (I know very few people who had the first kid under the age of 30). And would everyone have 3 kids? Don't forget to account for kids who die before they reproduce too.