How can you make number one disappear by adding something to it?

Here is a mathematical challenge that will not only engage your brain but also measure your quick-thinking abilities. If you can successfully identify the missing number in such a short span, you are demonstrating exceptional intellectual qualities.

From a pack of 52 cards, I placed 4 cards on the table.

I will give you 4 clues about the cards:

Clue 1: Card on left cannot be greater than the card on the right.
Clue 2: Difference between the 1st card and 3rd card is 8.
Clue 3: There is no card of an ace.
Clue 4: There are no face cards (queen, king, jacks).
Clue 5: Difference between the 2nd card and 4th card is 7.

Identify four cards?

Forwards I am heavy, backward I am not. What am I?

What does this rebus puzzle mean?

I am written with two letters.
I said with the one.
I usually am seen with the two.

Who am I?

The product of three consecutive numbers is 7980.
Then the sum of these consecutive numbers would be?

There once were seven dwarfs who were all brothers. They were all born two years apart. The youngest dwarf is seven years old. How old is his oldest brother?

Christina makes tasty toast in a small pan. After toasting one side of a slice, she turns it over. Each side takes 30 seconds. The pan can only hold two slices.
How can she toast both sides of three slices in 1 & 1/2 instead of 2 minutes?

John can place six large boxes or nine small boxes into a carton.

Can you find out in how many cartons can he place sixty-six boxes in total?