Yoku! Not Magic Square

Yoku is a game to keep in training the mind similar to the game of magic square.The aim is to find the expression that produces the result shown on the outside of the grid square.Conversely magic square but the results can all be different and are different in number depending on the level.The game is played on a grid 4 X 4, then the expressions are of simple type (single operation).The expression must start with a digit and must be valid.You can get a hint to know some of the numbers that make up the square.Easier to play than to explain, ... or not :-) ?Have Fun !