4=10 is a game on Google Play
This is a casual number puzzle game. 
The goal is to create an expression with 4 given numbers equal to 10 for example, 1+2+3+4=10.
there are a bunch of 4 digits numbers and 4 basic math symbols and a pair of parentheses
The player should solve 500 levels to finish the game.

I tried to write a code to find the solutions and in the "Hardest" branch of program finds the numbers that had the least number of solutions