Always in you, Sometimes on you;

If I surround you, I can kill you.

What am I?

A boy and a girl are sitting on the porch.
"I'm a boy," says the child with black hair.
"I'm a girl," says the child with red hair.
If at least one of them is lying, who is which?

Three doctors said that Bill was their brother. Bill says he has no brothers. How many brothers does Bill actually have?

What does this mean?

CCCCCCC

Find a 9-digit number, which you will gradually round off starting with units, then tenth, hundred etc., until you get to the last numeral, which you do not round off. The rounding alternates (up, down, up ...). After rounding off 8 times, the final number is 500000000. The original number is commensurable by 6 and 7, all the numbers from 1 to 9 are used, and after rounding four times the sum of the not-rounded numerals equals 24.

Open a Laptop which is password protected. Hint for the password is given as below:

1 mobile 3 books 2 Boards 1 night 4 balls 2 lighters 1 ghost 1 hat 3 watches

They are three errirs in this question. Can you find them?

Can you find the next number in the below sequence
3 , 7 , 10 , 11 , 12 , 17 ?

I come in different shapes and sizes.
Parts of me are curved, other parts are straight.
You can put me anywhere you like,
but there is only one right place for me.
What am I?

What can you deduce from the following BrainBat?

CRY
LMKI