Replace the question mark with the correct number, given the pair of numbers exhibits a similar relationship?

? : 3839 :: 11 : 1209

Can you find the odd one out from the below words ?

First Second Third Forth Fifth Sixth Seventh, Eighth Nine Ten Eleven Twelve.

Can you solve below mathematical equation?

2^1234 - 2^1233

I have a hole in my back and legs I lack.
I live where I can’t breathe and I eat without teeth.
What am I?

There was once a college that offered a class on probability applied to the real world. The class was relatively easy, but there was a catch. There were no homework assignments or tests, but there was a final exam that would have only one question on it. When everyone received the test paper it was a blank sheet of paper with a solitary question on it: 'What is the risk?'.Most students were able to pass, but only one student received 100% for the class! Even stranger was that he only wrote down one word!
What did he write?

In the four images below, can you find the odd one out?

There are 2 people near the river and both of them want to get on the other side. The boat can only take one of them. But they got across.
How?

Find the Next Number in the Sequence

2 9 3 1 8 4 3 6 5 7 ?

What does this rebus mean?

O
N
C
E
TIME

Using four sevens (7) and a one (1) create the number 100. Except for the five numerals, you can use the usual mathematical operations (+, -, x, :), root and brackets ()