I never was, am always to be,
No one ever saw me, nor ever will,
And yet I am the confidence of all,
To live and breathe on this terrestrial ball.
Who am I?

Our dear Admin has a locker in a bank.
But, he has forgot the key to open the locker.
Fortunately, he remembers some things which may help you to help him.
· Key is a four digits number (eg.1234 or 9876)
· Every digit is different
· It starts and ends with an odd number and has two even numbers in the middle.
· 19 and 519 go into it exactly.

What is the key which will open the locker?

The digits 0-9(0,1,2,3,4,5,6,7,8,9) can be rearranged into 3628800 distinct 10 digits numbers.

How many of these numbers are prime ?

Romila appeared for a maths exam.She was given 100 problems to solve.she tried to solve all of them correctly but some went wrong.Any how she scored 85.Her score was calculated by substracting 2 times the number of wrong answers from the number of correct answers.Can you tell how many problems she solved correctly?

Neha has 16 pairs of white socks and 16 pairs of brown socks.She keeps them all in the same drawer.If she picks out 3 socks at random what is the probability she will get a matching pair?

I never was, am always to be,
No one ever saw me, nor ever will,
And yet I am the confidence of all,
To live and breathe on this terrestrial ball.
Who am I?

Our dear Admin has a locker in a bank.
But, he has forgot the key to open the locker.
Fortunately, he remembers some things which may help you to help him.
· Key is a four digits number (eg.1234 or 9876)
· Every digit is different
· It starts and ends with an odd number and has two even numbers in the middle.
· 19 and 519 go into it exactly.

What is the key which will open the locker?

The digits 0-9(0,1,2,3,4,5,6,7,8,9) can be rearranged into 3628800 distinct 10 digits numbers.

How many of these numbers are prime ?

Romila appeared for a maths exam.She was given 100 problems to solve.she tried to solve all of them correctly but some went wrong.Any how she scored 85.Her score was calculated by substracting 2 times the number of wrong answers from the number of correct answers.Can you tell how many problems she solved correctly?

Neha has 16 pairs of white socks and 16 pairs of brown socks.She keeps them all in the same drawer.If she picks out 3 socks at random what is the probability she will get a matching pair?

I never was, am always to be,
No one ever saw me, nor ever will,
And yet I am the confidence of all,
To live and breathe on this terrestrial ball.
Who am I?

Our dear Admin has a locker in a bank.
But, he has forgot the key to open the locker.
Fortunately, he remembers some things which may help you to help him.
· Key is a four digits number (eg.1234 or 9876)
· Every digit is different
· It starts and ends with an odd number and has two even numbers in the middle.
· 19 and 519 go into it exactly.

What is the key which will open the locker?

The digits 0-9(0,1,2,3,4,5,6,7,8,9) can be rearranged into 3628800 distinct 10 digits numbers.

How many of these numbers are prime ?

Romila appeared for a maths exam.She was given 100 problems to solve.she tried to solve all of them correctly but some went wrong.Any how she scored 85.Her score was calculated by substracting 2 times the number of wrong answers from the number of correct answers.Can you tell how many problems she solved correctly?

Neha has 16 pairs of white socks and 16 pairs of brown socks.She keeps them all in the same drawer.If she picks out 3 socks at random what is the probability she will get a matching pair?