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Difficulty: 2 of 5 Latest: SOD revealed Rating: 5.00
......BTW....SOD IS A HEBREW WORD FOR SECRET!


A dialog between two mathematicians:


Ted: I have two numbers x and y, where x + y = z. The sum of the digits of x is 43 and the sum of the digits of y is 68.
Can you tell me the sum of the digits of z?

Fred: I need more information. When you added x and y how many times did you have to carry?

Ted: Let’s see. … It was five times.
Fred: Then the sum of the digits of z is 66.

Ted: That’s right! How did you know?



How did he know?

Credit: USC mathematician Solomon W. Golomb

(No Solution Yet, 1 Comments) Submitted on 2021-08-26 by Ady TZIDON   
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