If 5 cats catch 5 mice in 5 minutes, how long will it take one cat to catch a mouse?

Replace the question mark with the correct number in below Picture:

Find a 9-digit number, which you will gradually round off starting with units, then tenth, hundred etc., until you get to the last numeral, which you do not round off. The rounding alternates (up, down, up ...). After rounding off 8 times, the final number is 500000000. The original number is commensurable by 6 and 7, all the numbers from 1 to 9 are used, and after rounding four times the sum of the not rounded numerals equals 24.

Who can jump higher than a Mountain?

How is the moon similar to a dollar?

It is deaf, Dumb and Blind!!!

Still, always tells the truth. What is it?

I guess 76.8% of readers will like this riddle.

What's the least number of people should read this post?

What has one letter and starts with an E?

Can you solve this amazing hard number series problem?
7, 8, 10, 12, 16, 18 ?

I look at you, you look at me I raise my right, you raise your left. What am I?