One Click Calculator

My brother wasn't good at maths but playing a game that has to do with make random numbers using only one time each digit if calculator, he got better to calculations and then become the best math student 

So I was decided to make this game we played to an app so many students have the possibility to become better at math

The basic ideas is as I said to create this numbers only using once each digits of a calculator For example 

988 : (2^8-9)×4

Or 69 : 8×9-3