What goes through cities and fields, but never moves?

13 decks of cards have been mixed. What is the minimum number of cards that must be taken out from the above-mixed cards to guarantee at least one 'four of a kind?

There is a river to cross using a river raft and there are eight people (father, mother, policeman, thief, 2 daughters and 2 sons). No one knows to operate the raft except the adults and also excluding the thief. Only two people can go in the raft at a time. The raft should keep coming back and forth in order to pick and drop the people.
Rules to be followed:
Father: the father cannot stay in the raft or outside the raft without the presence of the mother.
Mother: the mother cannot stay in the raft or outside the rat without the presence of the father.
Thief: the thief is not allowed to stay with any of the family members unless there is a policeman.
Policeman: the policeman can travel with anyone.
2 sons and 2 daughters: they are not allowed to travel in the raft without the presence of an adult. They cannot either travel in the presence of only thieves without the policeman. The sons cannot be with their mothers without their father's supervision. The daughters are not allowed to be there with their fathers without the supervision of their mothers. But the daughters and the sons can be left unsupervised (as long as the other rules are applied).
What is the sequence that the people should follow in order to cross the river through the raft keeping in mind all the rules?
The rules are applicable not only in the raft but also outside the raft.

Take 9 from 6, 10 from 9, 50 from 40, and leave 6.

How Come ??

There is a box full of marbles,
all but two are blue,
all but two are green,
and all but two are red.

How many marbles are in the box?

Which city is three-fifths chick two third cat and 50% goat?

A thief is convicted in Mexico. He gets the death penalty. The judge allows him to say the last sentence to determine how the penalty will be carried out. If the thief lies, he will be hanged, if he speaks the truth he will be beheaded. The thief tells the last sentence and to everybody's surprise some minutes later he is set free because the judge cannot determine his penalty. What did the thief say?

What has 88 keys?

What does a man do only once in his lifetime, but women do once a year after they are 29?

Can you find the odd number in the following?

2716, 4135, 5321 and 7145