Ballpark — September 18, 2026
Answers to that day's 5 daily estimation questions.
Total US dollar bills in circulation
54 billion bills
Includes all denominations from $1 to $100.
Total gold ever mined in human history
200,000 tons
Most of it is still in use today.
Average lifespan of a digital file (hard drive)
5 years
Hardware failure is inevitable over time.
Total emails sent every day
350 billions
Includes business, personal, and spam.
Professional football stadiums in the NFL
30 stadiums
32 teams, but 30 primary stadiums.