Can you replace the question mark with the correct number?

Two boys wish to cross a river. The only way to get to the other side is by boat, but that boat can only take one boy at a time. The boat cannot return on its own, there are no ropes or similar tricks, yet both boys manage to cross using the boat.

How?

How many triangles can you find in this given picture?

You need to arrange three 7 and mathematical symbols to form number 1?

What has a ring but no finger?

Can you name some countries which do not have the alphabet 'A' in them?

How many minutes are there in Feb 2017?

Note: The shortest answer is the correct answer.

Solve the puzzle by telling what does below picture means.

Jack was having a candle light dinner with his girlfriend. Suddenly a cold gush of wind entered through the open window and three of the ten candles were extinguished. Assuming that none of the other candles were extinguished.

How many candles are they left with in the end ?

I have a five and a three-gallon jar. Assuming there is an infinite supply of water, how can I measure one-gallon water?