Calculate 4 numbers to get 10

About Calculate 4 numbers to get 10 Android App

It is a simple application that displays only four numbers from 1 to 9 at random.
Let's add, subtract, multiply and divide these four numbers to 10.
Of course in mental arithmetic.

Think of it as training to create a soft head.

For now, the answer example is displayed.
However, there is not always one correct answer.
For example, the numbers 2,4,5,8

(5 - 4) * 2 + 8 = 10
(8 - 4 - 2) * 5 = 10

In this way, there can be multiple formulas.
Please consider many ways.