During which month do people sleep the least?

Next Number in the Series,

5, 16, 49, 104, ?

What's the next in the series?

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

What makes this number unique: 8,549,176,320?

Considering the below equation:

V + II - VI = 10
IV - X + VIII = 20
IV - VII + VI = 30

Then, I + II + III = ?

Begin with a word, five letters to my name,
Remove the first and last but I am the same
Take out my middle and still, I remain.
What word am I?

Two boys were admitted to a school. When the headmaster asks them about their parents, they tell him that they have same parents (father and mother). On further inquiry, it turns out that they both share the same date for their birthday.

"Are you twins," ask the headmaster.
"No," replies the boys.

Is it possible?

Place the numbers from 1 to 9 in the circles in a manner that each side of the triangle sums up to 17.

I am lying and I always lie. Tell me whether I am lying or telling the truth.

Find the missing number in the series below

13 -21 34 -55 ? -144