(assuming it's A + A = B, there are still 4 sequences that could be if every number is an integer between 0 and 9, but if they remembered one of the numbers was

(assuming it's A + A = B, there are still 4 sequences that could be if every number is an integer between 0 and 9, but if they remembered one of the numbers was a 1 it would drop the possibilities down to only 1 + 1 = 2)