Mathematical Riddles

What has to be broken before you can use it?

I’m tall when I’m young, and I’m short when I’m old. What am I?

What month of the year has 28 days?

What is full of holes but still holds water?

What question can you never answer yes to?

What is always in front of you but can’t be seen?

There’s a one-story house in which everything is yellow. Yellow walls, yellow doors, yellow furniture. What color are the stairs?

What can you break, even if you never pick it up or touch it?

What goes up but never comes down?

A man who was outside in the rain without an umbrella or hat didn’t get a single hair on his head wet. Why?