I would like to create a regex that will validate that a string is an equation made up of a **single** digits and either the `*` or `+` operator and is no longer than 100 characters. So these would be valid:

 1+2*3*8+0
 9
 9*9

And these would **not** be valid:

 1++1
 12+1
 2*25
 1+
 47
 +
 +1
 11

I came up with the regex below to accomplish this:

 ^(\d{1}[\+\*]{1}){0,99}\d$

Which *appears* to work, but I'm curious if there is a cleaner way to accomplish this. Any suggestions or is this about as clean as it gets?

It is saved [here][1] if you would like to play with it.


 [1]: http://regexr.com/3cune