
Originally Posted by
ThePerfectHacker
They are all useful.
Examples,
1)Einstein found a way of describing space through "Differencial Geometry", a math topic which probably had no application until then.
2)In Quantum Mechanics, Homotopy groups appear, another supprising application of pure math.
3)Mathematical Logic can sometimes be applied to computer science.
...
Now, if all these people had your approach and said, well, let me never use it. That will never had happened.
As I said, the is a standard math, all mathematicians learn.
You should first learn these different fields of math first before you can complain about them and say they are useless.