Evolution progress while at Training Room

I should have known this earlier, but it is better to be late than never.

You need to know how many stars he/she is before you put your hero in the training room.

Also, you already know how many stones you need for each evolution:

120 for 2* to 3*

320 for 3* to 4*

840 for 4* to 5*

Then, this is the way you find out how far you have collected the evolution stones.

Here is my Miya at the Training room. She is 3 star.

So, I have 240 more to evolve her from 3* to 4*. Then, I have already strengthened her twice. 320 - (40 x 2) = 240.

Still very long way to go towards her 5 star evolution.