How many pluses should we put between the digits of 987654321 to get a total of 99, and where?

For an extra income, John decided to work at a Hotel for one hour daily. The manager offers him that they will pay him $11 after every 11 days.
However, John offered a different proposition to the manager. The offers stand as:
He will be paid just a penny on his first day.
Two pence will be paid on the second day,
Four pence will be paid on the third day.
And so on till the 11th day.

Should the Hotel manager accept his offer?

A man is approaching a broad and barren land. He has a package with him. If somehow, he is unable to open the package before reaching the land, he will die.

Can you guess what is present in the package?

Find the next number in the series?
2, 12, 36, 80, 150, 252, 392, _ ?

Who has married many women but was never married?

Can you place three balls such that the equation shown in the picture holds true?

What is always in front of you but can’t be seen?

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?

Can you find the odd number in the following?

2716, 4135, 5321 and 7145

A man dies of old age on his 25 birthday. How is this possible?