What goes up but never comes down?

I noticed one of the words in the oxford dictionary is spelled incorrectly. What about you?

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

They do not possess flesh or feathers or scales or bone
But still, they are blessed with fingers and thumbs of their own.

A man has a barrel filled with oil that weighs 100 pounds, and then he puts something into it. Now the barrel weighs less than 100 pounds. What did he put in the barrel?

He loves to dance, twist and prance, he shakes his tail, and as a way he sails, wingless he flies into the sky. What is he?

why number 8549176320 is one of a kind?

Find the next number in the sequence

1, 2, 6, 21, 88, __?

We have four gears with below features=> Both Gear A and D has 60 teeth=> Gear B has 40 teeth=> Gear C has 20 teeth=> Every two minutes, Gear B makes 25 full turns.What is the relative speed of Gear A and Gear B?

What has no start, end, or centre?