Before Mount Everest was discovered, what was the highest mountain in the world?

I am looking for a word that change both gender and number when i add the letter 'S'.

What Word am I Looking For ?

How many words can a pen with half refill write?

What can you hold in your right hand, but never in your left hand?

When can we add 2 to 11 and get 1 as the correct answer?

Can you calculate the probability of getting a sum of six when a dice is thrown twice?

Replace the question mark with the correct number.

2 + 2= 4
3 + 3= 18
4 + 4= 48
5 + 5= ?

On a certain day, John celebrated his birthday. Two days later, his older twin brother Jacob celebrated his birthday.

Is this even possible? How can it be?

Below is the sum of symbols in each row and column in the figure. Analyzing the figure, can you find out the value of the symbols?

It walks on 4 when its young, walks on 2 when it's older, and walks on 3 when its very old?