If 1111=R, 2222=T, 3333=E, 4444=N Then 5555=?

The answer to this question is Y. The logic followed here is determining the last letter of the number obtained on adding all the digits. 1111 = 1+1+1+1 = FOUR = R 2222 = 2+2+2+2 = EIGHT = T 3333 = 3+3+3+3 = TWELVE = E 4444 = 4+4+4+4 = SIXTEEN = N 5555 = 5+5+5+5 = TWENTY = Y