Unless there is in-app purchases

there is a "quest" in that you are asked to add 71 + 57 + 15 which equals 143, but the game reports this as being "wrong". How is it wrong?

I've taken many courses of math including Calculus 1 and 2, Geometry, Algebra 1/2, Statistics, and Discrete Math it would be nice to cover complex equations rather than focus on simple adding and subtracting shown in the trailer.

Is there any reward for playing hard mode? This game is tedious and boring in hard mode, because the opponent has lots of hp.

Ok so i've beem currently playing Mathoria: It All Adds Up during the place when you enter Addieren for the first time and you go to B-TEAM studios and you do the pen guy JOB and you find the guy that found the pen they ask you a question. Like for me it was 18 and 23 and i checked this 3 times and i got the answer 41 and i typed it in but the guy said "Ha! Just as I thought. It's not yours!" Im really confused and saved then load'd many times and I just couldnt do this. Can you fix this bug?...