I highly recommend the Numberphile YouTube channel for some really cool vids!!

I was recently watching their videos on Graham’s Number and found out about this cool thing called Knuth’s up-arrow notation.

3↑3 == Math.pow(3, 3) == 27

3↑↑3 == 3↑(3↑3) == BigInt(3).pow(27) == 7625597484987

3↑↑↑3 == 3↑↑(3↑↑3) == Math.pow(3L, 7625597484987L) == ...

The Scala compiler says Math.pow(3L, 7625597484987L) equals Infinity. Not quite…3↑↑↑3 has 3.6 trillion digits but is definitely finite. And its not even close to Grahams number.

But we went from 27 to a number with 3.6 trillion digits in 2 steps. Like I said…that escalated quickly.

Watch the whole video for all the goodness: