There is a 2 - D plane filled with 3 digit, 2 digit and single digit numbers. A, B and C are 3 digit numbers. The digit at the hundreds place is the head and the digit at units place is tail of the number. There are no mirrors in this plane. So, no number can see its own tail. A, B and C are good friends. Since, A can see B's and C's tail, it tells them that they both are divisible by 4. B and C tell A that it is divisible by 2. One day a 3D Mathematician comes and adds A, B and C to form a 4 digit number. This new number (A + B + C), must be divisible by:
2
If B and C are divisible by 4; They are also divisible by 2. [All the numbers divisible by 4 are also divisible by 2 as their prime factorization will definitely contain 2]. Also, A is divisible by 2. Since A, B and C all are divisible by 2, the sum A + B + C is also divisible by 2.