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

An equation has been laid down using a few matchsticks. However, as you can see, the equation is not correct. Can you correct the equation if you are allowed to add or remove 5 matchsticks?

What does it mean?

I have holes on the top and bottom. I have holes on my left and on my right. And I have holes in the middle, yet I still hold water. What am I?

As you can see in the picture, you have a hole with dimensions 9 ft x 2 ft Also available is a wooden board with dimensions 6 ft x 3 ft Now you have to cover the hole with this board and you are allowed to cut the board into two pieces. Please see that the hole is completely covered and the boards should not overlap or extend beyond the edge. How will you cut the board?

What does this mean?

CCCCCCC

What can you see in the middle of March and April that you can never see in any other month?

What does this rebus mean?

O
N
C
E
TIME

What does a man do only once in his lifetime, but women do once a year after they are 29?

What is the next shape from answers A, B, C, and D figure?