14. In the equation on the right, the letters $a, b, c, d$ and “$\square$” represent one of the ten digits from 0 to 9. Among them, $a, b, c, d$ represent different digits. Find the sum of the digits represented by $a, b, c, d$.
【Key Points】Number Puzzle
【Answer】 $10,18,19$
【Analysis】As shown in the figure below
or
$$
a=5
$$
(1) When $c=3$, $b+d$ carries over, take $b+d=10$ or $b+d=11$
Then $a+b+c+d=5+3+10=18$ or $a+b+c+d=5+3+11=19$
(2) When $c=4$, $b+d$ does not carry over, can only take $b+d=1,0+1=1$ which meets the requirement, at this time $a+b+c+d=5+4+1+0=10$.