The math-teaching website Math Is Fun gave children a thought experiment: see how long it would take to count to various milestone numbers. To count to 100, the author said, took them about 25 seconds; about ten minutes to count to one thousand, and so on.

To count to one billion, says the author, would take over 100 years.

It’s unclear if this calculation accounts for breaks for food, sleep, and so on. Assuming no breaks, if you counted once each second, it would still take over 30 years (one billion seconds = 31.69 years). If you counted quickly and were able to count four numbers each second (easy in the beginning, but considerably harder as the numbers get bigger), it would only take under a decade: 7.9225 years, to be specific.

Obviously, no one has ever done this, but marathon counting sessions (to lower numbers) are nothing new. Math Is Fun notes that, in 2007, a man named Jeremy Harper counted to one million for charity — with breaks for food and rest, of course — and it took him just under three months. Similarly, YouTuber Mr. Beast counted to 100,000 straight through, and it took him 40 hours.