Question

Find A and B in the addition.

	A
+	A
+	A
B	A

Answer 1

The sum of three A’s is a number whose one's digit is A.

The sum of two A’s must be a number whose one's digit is 0.

This happens only for A = 0 and A = 5.

If A = 0, then the sum is 0 + 0 + 0 = 0, which makes B = 0 too.

We do not want this, so we reject this possibility.

So, A = 5.

Therefore, the puzzle is solved as shown below.

	5
+	5
+	5
1	5

That is, A = 5 and B = 1.