What does this mathematical rebus means ?

What is both possible and impossible at the same time?

what does the below math rebus puzzle mean?

Find the next number in the sequence

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

John drives to his office at 20km/hr. After reaching the office, he realizes that today is a holiday. He went back at an average speed of 30km/hr. Discounting the time spent in the stoppage what was the average speed of his journey?

I am sure no one can have two things for dinner. what are they?

You measure my life in hours
I serve you by expiring
I vanish faster when I am thin
and slower when I am thick
The wind is my energy
What am I?

_ _ _ IE _ _
_ _ _ IE _
_ _ IE _ _
_ _ IE _
_ _ _ _ IE

Like you see, some letters have gone missing from these words that contain the IE pair at some or the other place. The letters that will be used to fill the blanks are given below. Use them and form meaningful words. Can you do that?

A, C, D, F, H, K, L, M, N, N, O, R, R, S, S, S, T, T, Y and Y.

What question can you never answer yes to?

You are given four results as below:
1111 = F
2222 = E
3333 = T
Then, can you find out how to code 4444?