abcd-numar de patru cifre ,unde a≠b≠c≠d;
a. d=[0,2,4,6,8];⇒a,b,c-cifre impare;
b. a+b+c+d=12;
c. b=0⇒d≠0⇒d=[2,4,6,8];
⇒a+0+c+2=12⇒a+c=10⇒a,c=[[1,9],[3,7],[4,6],[6,4],[7,3],[9,1]];
⇒a+0+c+4=12⇒a+c=8⇒a,c=[[1,7],[2,6],[3,5],[5,3],[6,2],[7,1]];
⇒a+0+c+6=12⇒a+c=6⇒a,c=[[1,5],[2,4],[4,2],[5,1]];
⇒a+0+c+8=12⇒a+c=4⇒a,c=[[1,3],[3,1]];
⇒sunt 6+6+4+2=12+4+2=16+2=18 numere care indeplinesc conditiile problemei;