Veritasium: Why is this number everywhere?

Humans are surprisingly bad at picking truly random numbers. When asked to name a random number between 1 and 100, many people consistently choose 37. This phenomenon, known as the 'blue-seven phenomenon' for colors and numbers, reveals deep patterns in our intuition.

In a massive survey with over 200,000 responses, 37 emerged as one of the most commonly selected numbers, alongside 7, 73, and 77. These numbers feel more 'random' to us, even though the choices are far from truly random.

Why 37? Psychologically, people tend to avoid extremes or round numbers like 50 or multiples of 10, favoring odd and prime numbers. 37 is prime, rare in everyday life, and lacks a simple formula to predict the next prime, making it feel unique and random.

Mathematically, 37 holds a special place: it is the median second smallest prime factor of all numbers, meaning half of all integers have 37 or less as their second prime factor. This rare property highlights 37's unique role in number theory.

The 'secretary problem' or 'marriage problem' uses the number 37 as a key strategy: when faced with sequential choices, the optimal decision is to reject the first 37% of options to learn the field, then select the next best option. This maximizes the chance of the best pick.

This 37% rule applies beyond math to real-life decisions like choosing a job or partner. It reflects how 37 is not just a number but a guide to optimal decision-making, blending intuition and probability for better outcomes.

The number 37 also appears in many surprising contexts—from cultural references like Shakespeare's 37 plays to everyday objects and measurements. One enthusiast has collected thousands of instances of 37 appearing in the world, showing its pervasive presence.

Despite its mathematical and psychological significance, 37 remains a number wrapped in mystery and fascination. Its frequent appearance in culture, math, and human intuition makes it a symbol of the hidden patterns shaping our world.