Allow me to assume that the moment of birth and the moment of death are identical.

Thus the person lived exactly 36 years.

Also allow me to assume that each year is 365 days. Actually, each is is APPROXIMATELY 265.24 days (AND the day actually gets longer each year as a result of tidal effects), but for the purposes of this estimate I will use 365 days per year.

The usual 24 hours per day, and normal hours and seconds, will apply.

36 years
13,140 days
315,360 hours
18,921,600 minutes
1,135,296,000 seconds

Gives you a good idea of about how big one billion actually is.

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