Each Friday morning I post a riddle to get you to think outside the box and exercise your brain.  If you are stumped, share it with a friend or colleague and try to figure it out together.

I’ll confirm answers in the afternoon so don’t worry if you don’t see your comment posted right away. I want to give everyone a chance to guess.

This week’s brain teaser:  Two spies want to infiltrate an enemy military base but to enter they must give the correct countersign at the gate so they wait nearby undercover to overhear the countersign from other soldiers as they pass.

One soldier comes and is given the sign “6”; the soldier answers “3” and is allowed to pass.  Soon a second soldier approaches and is given the sign “12”; he responds “6” and is allowed to pass. Thinking he had cracked the code the first spy goes to the gate but when he is given the sign “10” and says “5” he is shot dead. The second spy, who witnessed everything is able to figure out the code so when he approaches and is given the sign “8” he confidently answers correctly.

What was the answer that the spy gave and why?