Can you solve this?

There are two spies who need to get into an enemy's military base. In order to make it into the base, they must give the correct countersign to the man standing guard at the gate once he gives his sign. They wait nearby so that they can watch other people come and go so as to figure out the countersign. One soldier steps up to the gate and guard gives the sign, "6." The solider provides the countersign, "3." The guard lets the soldier in. Another soldier comes up. The guard says, "12" and the soldier answers with, "6." The guard lets that solider in. The first spy believes that he has figured out what the countersign is, so he steps up to the gate. The guard says, "10." The spy replies with "5." The guard immediately shoots him dead. The other spy now understands what the countersign is. He steps up to the gate and the guard says, "8." The spy replies with the right answer and is allowed into the military base. What was the answer that the spy gave?

And solve this?

A prison has 23 cells, each with one prisoner in them. They do not have any way to communicate with one another while they are in their cells. Two switches hang on the wall in the rec room - switch A and switch B. There is an on and off for each switch, but they are both in unknown positions.

The prisoners are escorted, randomly, down to the rec room. Each time they are taken down to the rec room, they can flip one of the switches. During this task, a prisoner being taken to the rec room can shout, "Every prisoner has been here." If they are right, then they all go free. If they are incorrect, then they will all be executed.

Before the task begins, they are allowed to gather for a planning session so that they can figure out a plan. What should they do to ensure they go free?

From the bestseller book "King of riddles", Karen is back with more riddles This time, the riddles are ranged from medium to hard difficult. Get ready to challenge your brains today

The Queen Of Riddles - pocket, Engelska, 2020