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?

If 1+9+8=1, what is 2+8+9?

In a concert, Christina is performing a dance show with her group.
At 10:00, she and her crew were dancing in an absolutely straight line. At that time Christina was standing in 4th position from both the front and back end of the row.

What was the size of her crew?

In the given figure, you can see that four match sticks are used to form a square. Can you form five squares by using six matches?

The day before yesterday I was 25 and the next year I will be 28. This is true only one day in a year. What day is my birthday?

You can see three almost identical images below. Can you spot the odd one out from them?

Find the next number in the sequence

1, 2, 6, 21, 88, __?

Three fair coins are tossed in the air and they land with heads up. Can you calculate the chances that when they are tossed again, two coins will again land with heads up?

John went to a parrot shop in Mexico, and the parrot owner told him that his parrot is so unique that he repeats everything he hears. John got excited and immediately bought the parrot. John went home and spoke many words, but the parrot does not repeat anything.
He went again to the parrot shop and complaint to the shopkeeper, but the shopkeeper never lied. Explain?

What does the following represent?

N N N N N N N

A A A A A A A

C C C C C C C