Can you find a pattern and the missing number in the series given below?

100, 155, 258,? , 584, 819.

What has 13 hearts but no other organs?

The dirtier I get, the whiter I look. Who am I?

If 24H in a D => 24 hours in a day.
What does "64S on CB" stand for?

What three numbers, none of which is zero, give the same result whether they’re added or multiplied?

What does below chemistry rebus means?

John Went to the nearby store in a Mall to buy something for her home. Below is the conversation between the two:

John: How much for the one?
Shopkeeper: It is $2
John: How much for the Eleven?
Shopkeeper: It is $4
John: How much for the Hundred?
Shopkeeper: It is $6.

What is John buying?

You measure my life in hours
I serve you by expiring
I vanish faster when I am thin
and slower when I am thick
The wind is my energy
What am I?

I am under you when I am whole.
I shift above you if you remove the first letter.
I come all around you if you remove the second as well.

Can you tell me who I am?

How many sides does a circle have?