What is the next number in this series?

4,12,84,3612....

In this image, you can see three almost identical Doraemon images. Can you spot the odd one out from them?

If two fifty-foot ropes are suspended from a forty-foot ceiling that is twenty feet apart, how much rope will you be able to steal if you have a knife?

When I get multiplied by any number, the sum of the figures in the product is always me. What am I?

You may enter, but you may not come in. I have space, but no room. I have keys, but open no lock. What am I?

Christina is older than Kareena and Karishma. Katrina is older than Karishma and younger than Kareena. If Kareena has a brother named John, who is older than Christina, who's the youngest?

What has no start, end, or centre?

Nine marbles are arranged in the image below. Can you slide two marbles to form a square?

How is the moon similar to a dollar?

I have four wings but can't fly.
I express no emotions.
I am found on the exact spot every time you look.
I keep toiling away with a little sound.

Do you know what am I?