Can you replace the question mark with the correct letter?

6 + 6 + 6 = N
7 + 7 + 7 = E
8 + 8 + 8 = R
0 + 0 + 0 = ?

What goes up but never comes down?

What does this mathematical rebus means ?

You are mixing a mixture of cement and Sand with five gallons of water. You have a garden hose giving you all the water you need. The problem is that you only have a four-gallon bucket and a seven-gallon bucket and neither has graduation marks. Find a method to measure five gallons.

Manish and Manoj play 5 games of chess.
Both Manish and Manoj win the exact same number of games. There is no tie at all.

How?

What is the word or phrase?

Why is the Hole below a Lock?

I am a white box having no key or lid.
Yet there is a golden treasure inside it.

What Am I?

If 21x = 79x, what is the value of x?

Two batsman each on 94 runs. Seven runs needed to win in last 3 balls. Both make 100*. How?