Find the Next Number in the Sequence

2 9 3 1 8 4 3 6 5 7 ?

With pointed fangs I sit and wait; with piercing force I crunch out fate; grabbing victims, proclaiming might; physically joining with a single bite. What am I?

How do you go from 98 to 720 using just one letter?

Four men were in a boat on the lake. The boat turns over, and all four men sink to the bottom of the lake, yet not a single man got wet! Why?

A pond had 60 fish, out of which, all but 20 died.
How many fishes are now present in that pond?

A man plots the murder of his wife. His plan is full proof. Nobody saw them leaving their house. He stabbed her with a knife while driving. She died on the spot. He threw her body in a valley. He threw the knife carefully wiping his finger prints on a random garbage bin. Then he went back to his home and no one was watching him this time as well.

After an hour, he was called by the local police department who informed him that his wife was murdered. They asked him to reach the scene of crime immediately. But as soon as he arrived at the crime scene, he was arrested by them.

How did the police know that he himself is the murderer?

What is next number in the pattern below:

131 517 192 123 ?

The richest man in the city Mr Rechard is kidnapped. James Bond is appointed to the case. At the crime scene, a note is found written by Mr Richard. The note read:

"First of January, Fourth of October, Fifth of March, Third of June."

James Bond knew that somehow, the killer's name was hidden in the note. The following were the suspects:

Jack Richard, the son and the heir of property.
John Jacobson, the employee of Richard.
June Richard, the wife of Richard.

James Bond took only a few moments to deduce the killer's name. Can you tell who was the killer?

In particular commonwealth games, a female participant won silver and gold medals for a single event.

How can this be possible?

Use the digits from 1 up to 9 and make 100.

Follow the rules.
=> Each digit should be used only once.
=> You can only use addition.
=> For making a number, two single digits can be combined (for example, 4 and 2 can be combined to form 42 or 24)
=> A fraction can also be made by combining the two single digits (for example, 4 and 2 can be combined to form 4/2 or 2/4)

Question: how can we do this?