What word begins and ends with an E, but has only one letter?

What has one letter and starts with an E?

Can you count the number of quadrilaterals in the picture below?

It's pretty hard to give up.
If you remove a part of it, you will be left with a bit.
Even if you remove another part, the bit still remains.
Remove one more and it still remains.

What is it?

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?

There is a place where if I stand up straight, I will still be considered sideways.

What number divided by 4 is the same as that number minus 4?

After teaching his class all about Roman numerals (X = 10, IX=9 and so on) the teacher asked his class to draw a single continuous line and turn IX into 6. The teacher's only stipulation was that the pen could not be lifted from the paper until the line was complete.

I know a ten-letter word in the English language which can be typed using only the top rows of the computer keyboard.

We are a group of eight brothers. We consider the weak, yet we protect the king in every battle. If we move ahead, we never turn back. Who are we?