Many have heard it, but nobody has ever seen it, and it will not speak back until spoken to. What is it?

We are a group of eight brothers. We consider the weak, yet we protect the king in every battle. If we move ahead, we never turn back. Who are we?

I cry without having a voice.
I fly without having wings.
I bite without having teeth.
I whisper without a mouth.

Who am I?

Take one out and scratch my head, I am now black but once was red. What am I?

A mile-long train is moving at sixty miles an hour when it reaches a mile-long tunnel. How long does it take the entire train to pass through the tunnel?

Which number should replace the question mark?

15 caves are arranged in a circle at the temple of doom. One of these caves has the treasure of gems and wealth. Each day the treasure keepers can move the treasure to an adjacent cave or can keep it in the same cave. Every day two treasure seekers visit the place and have enough time to enter any two caves of their choice.

How do the treasure seekers ensure that they find the treasure in the minimum number of possible days?

One is to three as three is to five and five is to four and four is the magic number.
What is the pattern?

what does the below math rebus puzzle mean?

I guess 76.8% of readers will like this riddle.

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