# Why is 42 the seed used in RunPCA() in Seurat?

The RunPCA() in Seurat 3.0 function has seed.use=42 by default. How does one choose a seed number? Is this chosen simply because it is the Answer to the Ultimate Question of Life, the Universe, and Everything? Or maybe Lewis Carroll's curious obsession with the number?

• Any integer >= 0 (but not too large) can make a good seed, 42 is a popular choice for the reasons you note, residentmar.io/2016/07/08/randomly-popular.html and blog.semicolonsoftware.de/the-most-popular-random-seeds Jul 9, 2019 at 13:31
• The authors of the Mash and sourmash algorithms use 42 as the seed for the MurmurHash3 k-mer hashing function, and I understood this to be a nod to the Hitchhiker's Guide as you suggested. So the idea isn't completely without precedent. 😀 Jul 9, 2019 at 13:37

The choice of 42 could therefore well come from one of the reasons you propose. Only the authors of the programs could confirm.