Find the next number in the sequence

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

You have to fill the below given grid in a manner that every row and column contains the digits 1 to 6. Also, make sure that the squares that are connected with each other must contains the same digit.

Solve the rebus riddle in the picture below.

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?

Which is the smallest number that you can write using all the vowels exactly once?

There's one "sport" in which neither the spectators nor the participants know the score or the leader until the contest ends.

What is it?

It has horns but can’t beep. It is like to bleat but It is not a sheep. What is it?

John and Jill are madly in love with each other. To remind Jill of his pure love, John wants to send her a ring by post but in their country where burglary is quite prominent, any package that is not locked comes under the risk of being stolen for the contents.

John and Jill possess many padlocks but neither one of them has the other key.

Can you find a way John can send the ring to Jill safely?

What's the next in the series?

H, Be, F, S, Mn, Kr, In, Gd, Tl, ?

I have 50 feet long of cloth, I need to create 50 handkerchiefs each size of 1 foot. I take one minute to cut a 1-foot handkerchief. So how long will it take to cut 50 handkerchiefs?