I started by getting all the possible sets of 3 non-repeating digits.
From there, I looked at figuring out all the combos to get D + E = Y and N + R = E. What made this challenging was if there was a (I could not remember the actual word for it) carryforward value of 1 into the next column. For ex 1 + 9 = 10, the 0 would be in the reference column but the 1 would be a carryforward, so for N + R = E, I also needed to factor in N + R + 1 = E
Mod was involved. And then it was just a matter of repeating the logic and excluding invalid combos
