### A generation is about one-third of a lifetime. Approximately how many generations have passed since the year 0 AD?

## Solution:

We are looking for generations passed in history. The general assumptions are:

- There are 10
^{11 }seconds in 1 history - In 1 generation, there is 1/3 of a lifetime.
- In half a lifetime, there are 10
^{9}seconds

Therefore, the number of generations passed is

☚