re: Pointless theoretical estimation question re: ants

1st, consider the lifespan of an ant. Let's call it a 6 months (little more or little less), half a year to be even

2nd, how many ants in a colony? Roughly 100k-500k, we'll call it 100k for even numbers

3rd, how many colonys do we have at this exact moment? Let's say 100 million

4th, how long have ants existed? Let's say they've existed since 100 million years ago, it's actually between 110-130 million

5th, let's do the math. 100 million ants X 2 ants per year X 100 million years. We can even ignore the 2 ants (6 month lifespan) bc it's not important for an order of magnitude. So the rough total would be 100 million X 100 million, roughly 1x10^16, or 10 quadrillion. Multiply it by 2 and you have 20 quadrillion, fairly close to OP's number when considering orders of magnitude

Tldr: 20 quadrillion in my calculator