The Secret Life of 37
The Hook
What if the number you randomly chose wasn't random at all? Derek Muller presents a fascinating investigation into one of mathematics' most persistent puzzles: why do humans consistently gravitate toward certain numbers when asked to pick randomly? His evidence spans thousands of survey respondents, prime factor analysis, and even the mathematical framework for life's biggest decisions. This isn't just a curiosity — it's a window into how our minds actually think about randomness.
The Blue-Seven Phenomenon
Muller begins by introducing what psychologists have long documented: when asked to pick a color or a number randomly, people reliably select blue and seven across dozens of different cultures. "Psychologists have a name for this pattern," Muller explains, "the blue-seven phenomenon." This is the foundation of his investigation into whether an equivalent number exists for the 1-100 range.
The Veritasium team conducted what appears to be the largest survey ever on random number selection — receiving 200,000 responses. The results were remarkably consistent across different sample sizes. "It's fascinating to watch how consistent these supposedly random numbers are," Muller observes, noting that from 10,000 to 100,000 respondents, "the distribution barely changes suggesting that people from all around the world think about random numbers in a particular way."
The findings were clear: ignoring extremes like 1 and 100 because they're literally in the question itself, and ignoring 42 and 69 because they're references to popular culture ( Hitchhiker's Guide and sex), a few numbers stand out as feeling more random than others. The most selected numbers were 73, 77, and 37.
"The actual least picked number in the first question was 90 followed by 30, 40, 70, 80 and 60 — multiples of 10 apparently don't seem that random."
This observation lands hard because it reveals something counterintuitive: our sense of what feels random is actually highly patterned. We're not picking numbers at all — we're selecting from a narrow, culturally-informed palette.
Why Odd Numbers Feel More Random
Muller digs deeper into why certain numbers feel more random than others. One argument he presents is that people perceive even numbers as less random than odd numbers. "People think that even numbers are less random than odd numbers," he argues, and five feels not random while nine feels too extreme.
This is backed up by the fact that every one of the top numbers in their survey consisted of threes and sevens. "Three and seven were the most selected digits on both questions." The pattern isn't coincidence — it's psychology.
But there's also a mathematical case for why primes feel more random than composites. Muller notes that primes don't appear as much in our lives: pixel counts, fruit boxes, square footage — we live in a composite world with multiple dimensions that multiply together. "We just don't see primes much past the single digits."
"Second, we don't have a formula for primes — if you have a prime number and you want to find the next one, you have no choice but to check every number until you find a prime." This mathematical argument explains why primes feel more random: they occur essentially at random in the distribution of integers.
The 37% Rule
The most compelling part of Muller's investigation is his exploration of how 37 actually matters practically. He introduces what mathematicians call the secretary problem or marriage problem — an optimal stopping theory that tells us when to make decisions.
"So your best bet is somewhere in the middle," Muller explains, "there you know at least some information from the options you've seen and you have some choice to select or pass." The mathematical solution: first explore 37% of options to learn what's out there, then start selecting the first option that's better than everything you've seen.
"Explore and reject 37% of options just to get a sense of what's out there and then select the first option to come along that's better than all of the ones you've seen — and your chances of success using this method are also 37%."
This works not just for hiring employees or finding a partner, but for practical decisions like whether to rent an apartment or accept a job offer. The mathematics suggests that spending roughly 37% of your time exploring — say, the first 3.7 years of a ten-year dating window — gives you the optimal chance of selecting correctly.
Counterpoints
Critics might note that while Muller presents compelling evidence for why people choose certain numbers, he's working with survey data from Reddit and his own channel audience — not a scientifically random sample. The findings are consistent across 200,000 responses, but self-selected audiences tend toward similar psychological patterns anyway.
Additionally, the 37% rule is mathematically elegant but practically difficult to apply: you rarely know how many total candidates exist in any real-world scenario. The rule works perfectly only when you have a known number of options — which most life decisions don't provide.
Bottom Line
Muller's strongest move is connecting mathematical curiosity to practical decision-making. The journey from why we pick 37 to why we should use the 37% rule transforms what could be a trivial observation into something with genuine life application.
The piece's biggest vulnerability is that it leans heavily on one investigation — the Reddit poll and survey data — without formal academic validation. But the core insight remains powerful: we're not as random as we think, and mathematics can actually help us make better decisions. The number 37 isn't just a curiosity — it's a lens for understanding human psychology itself.