Find The Next Number In The Sequence

30 10 15 13 0 16 -15 ?

I am a white box having no key or lid.
Yet there is a golden treasure inside it.

What Am I?

A blonde put eyeliner on her head. Why?

There is a box full of marbles,
all but two are blue,
all but two are green,
and all but two are red.

How many marbles are in the box?

The following "Brain Bat" means Slow Down.
S
L
O
W

Using the same logic, can you tell us what does the following Brain Bat means ?
E
V
I
G

John killed hundreds of people mercilessly and yet the police were not able to put her behind the bars. Why?

Find the number of squares in the below-given picture.

What does a man do only once in his lifetime, but women do once a year after they are 29?

Can you find out the next digit in the following series ?

0, 0, 1, 3, 2, 6, 3, 9, 4, 12, 5, ?

Rihana, Peeta, and Logan order a pizza for $10. Out of the three, Rihana and Peeta were quite hungry and ate 6 slices a piece, while Logan had just 2 slices.

Now, they want to split the cost among them fairly but due to the lack of change, they decide to round off the cost to the nearest possible dollar.

Can you find out the fairway which should be used to split the money?

What if the pizza was worth $11?