What is the next number in this matchsticks series riddle?

What is common among 11, 69, and 88?

My friends called me Iron59 because my parents are a chemist and a mathematician. What is my real name?

What can go up a chimney down, but can’t go down a chimney up?

If eleven plus two equals one, what does nine plus five equal?

I have a hole in my back and legs I lack.
I live where I can’t breathe and I eat without teeth.
What am I?

A woman shoots her husband.

Then she holds him under water for over 5 minutes.

Finally, she hangs him.

But 5 minutes later they both go out together and enjoy a wonderful dinner together.

How can this be?

Two trains start at the same time, one from Bangalore to Mysore and the other from Mysore to Bangalore. if they arrive at their destinations one hour and four hours respectively after passing one another, how much faster is one train running than the other?

What is the four-digit number in which the first digit is one-third the second, the third is the sum of the first two, and the last is three times the second?

Quickly Solve this riddle

7 - 4 + 3 * 0 + 1 = ?