Can you fill the blank with the correct number?

6 30 870 756030 _____

Find the next number in the series below

21 32 54 87 131 ?

In particular commonwealth games, a female participant won silver and gold medals for a single event.

How can this be possible?

Find out the missing number in the picture attached:

A man wants to cross the pit of fire which is 25 feet in length and he has 2 planks(fire resistant) 19 feet in length. How can he cross the pit of fire alive?

Take away my first letter, then take away my second letter. Then take away the rest of my letters, yet I remain the same. What am I?

What's the next in the series?

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

When I go in I might cause pain. I cause you to spit and ask you not to swallow. I can fill your hole. What am I?

The Little ant seems to be always confused. Do you know why?

A high school has a strange principal. On the first day, he has his students perform an odd opening day ceremony:

There are one thousand lockers and one thousand students in the school. The principal asks the first student to go to every locker and open it. Then he has the second student go to every second locker and close it. The third goes to every third locker and, if it is closed, he opens it, and if it is open, he closes it. The fourth student does this to every fourth locker, and so on. After the process is completed with the thousandth student, how many lockers are open?