Properties of the number 50

I will shortly be engaging with my 50th (!) birthday.

50 = 1+49 = 25+25 can perhaps be described as a "sub-Ramanujan" number.

I'm trying to put together a quiz including some mathematical content. Contributions most welcome. What does 50 mean to you?


Solution 1:

$50$ is the sum of three consecutive squares: $50=3^2+4^2+5^2$

Solution 2:

$50$ is the least integer that is $1$ more than a square but is not squarefree.