I assume the usual (though unstated) provisions that each letter stands for a different integer (0..9), and that none of the four "words" starts with zero.
There are two numbers for which a single solution:
for Y=2 -- 65 + 735 + 9532 = 10332
for Y=3 -- 75 + 625 + 9523 = 10223
For two other values of Y there are two solutions each:
for Y=4 -- 75 + 625 + 9524 = 10224
for Y=4 -- 65 + 735 + 9534 = 10334
for Y=8 -- 75 + 625 + 9528 = 10228
for y=8 -- 65 + 735 + 9538 = 10338.
+ 1