### An old man lives alone in a flat.

### Because of his old age, he is not able to move comfortably and hence most of the things are delivered to his home.

### On Friday while delivering the mail, the postman felt something suspicious in the flat and tried to look inside through the keyhole and he saw a blood-filled body of the old man.

### The police arrived at the scene.

### On the outside of the flat, they found two bottles of warm milk, a Tuesday newspaper, some unopened mails and some gifts.

### Who killed the old man and how did the police know who to arrest?

### Answer

Find The Answer For Old Professor Asked John To Write Down Number.

The professor has to add the rest of the digits, find the nearest number to the sum that is divisible by 9 and get the difference.

So, John gave the number 9646 to the professor. The professor will add the numbers (9 + 6 + 4 + 6) to get 25. The nearest number to 25 that is divisible by 9 is 27. And the crossed out number is 27 – 25.

This is a Maths trick that relies on the power of 9.