Replace the question mark with the correct number in the below-given picture?

In two decks of cards, what is the least amount of cards you must take to be *guaranteed* at least one four-of-a-kind?

There is a square piece of paper with a hole that is denoted by the circle on the top right side in the given picture. You have to cut the paper in a manner that it forms two and only two separate pieces of paper and then rearrange the pieces in a manner that the holes come in the centre of the paper.

On a bright sunny day, two fathers took their son fishing in the lake. Each man and son were able to catch one fish. When they returned to their camp, there were only three fishes in the basket. What happened?

PS: None of the fish were eaten, lost, or thrown back.

Can you find out the remainder when 3^300 is divided by 5?

There are 3 apples in the basket and you take away 2. How many apples do you have now?

Can you find the thief by just looking at the picture below?

What does it mean?

How many points are there on the globe where, by walking one mile south, then one mile east and then one mile north, you would reach the place where you started?

There is a shop where written:
Buy 1 for $1
10 for $2
100 for $3
I needed 999 and still only paid $3. How could this be financially viable for the shop-keeper?