Get % in Answer

Simply implementing the percentage as a unit factor, as we were used to, seemed to have been too simple, comfortable and intuitive for PTC.
Its a number format option in Prime.

In Mathcad when you typed % you got a predefined constant (0.01) which was then used as a factor when defining a variable and so it also could be used in the unit placeholder.

When we type % in Prime it looks like we get a predefined function in postfix notation which multiplies its argument by 0.01, but being a function it can't be used in the unit placeholder.

You could define % as a constant but you would have to use the trick with the "" to be able to create % as a variable name and therefore you still would not be able to just type % in the unit placeholder, you would have to copy the created variable name which is even more hassle than to use the  format menu.

There is also a difference in appearance when using the latter method - there is a larger space between the number and the %  character because of the hidden implicit multiplication character in between.  Sometimes this may be preferred.