Question 452389
It is impossible to obtain 3 using all the digits once, assuming the order of operations is followed.


Suppose the integers are a,b,...g in that order, with


*[tex \LARGE ab - \frac{c}{d} + \frac{ef}{g} = 3]


This implies 


*[tex \LARGE ab + \frac{ef}{g} = 3 + \frac{c}{d}]


The maximum value the RHS can attain is when c = 9, d = 2, in which RHS = 15/2. If this is the case, ab must be greater than or equal to 3*4 = 12, in which this is impossible. In all other cases, the maximum value of the RHS is smaller than the minimum value of the LHS, implying that equality is impossible to obtain.