0.739085133215160641312087673...

That is the value of a number where giving the cosine of it gives the same number.

In other words, cos(x) = x.

But not only that,

It is the ONLY real number where this is true.

But, that's not the only cool thing about it.

If you have a calculator near you, type in any number and keep pressing cosine.

The number will eventually converge to this number!

Try it yourself!

Enter a number here, and press the button to make it the cosine of it. Watch as it eventually converges.

Fun fact: The number was known since the 1860s, but only given a name in 2007.

The dottie number is also transcendental and irrational.