Find the next number in the sequence

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

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.

Quickly Solve this riddle

7 - 4 + 3 * 0 + 1 = ?

Can you complete the sequence puzzle?

AR TA GE CA LE VI LI _

I am the black child of a white father, a wingless bird, flying even to the clouds of heaven. I give birth to tears of mourning in pupils that meet me, even though there is no cause for grief, and at once on my birth, I am dissolved into air. What am I?

There are five vowels (a, e, i, o, u) in the English language.
Can you tell us a word that contains all these vowels?

Name one eight-letter word with 'kst' in the middle, 'in' the beginning, 'and' at the end.?

Using four sevens (7) and a one (1) create the number 100. Except for the five numerals, you can use the usual mathematical operations (+, -, x, :), root and brackets ()

How can you spell "White of an egg" in one word?
Hint: I know you can spell coke, poke, and joke.

What comes
Once in a Year
Twice in a Month
4 times in a Week
6 times in a Day