He found a hidden hot spring deep in the mountains.

This secret ceremony is a mysterious ritual passed down from ancient times.

He believes that there is a secret base on that island.

He is rumored to be a member of a secret society.

He was caught by the secret police.

You must never show this secret key to anyone else.

In Christianity, the Number of the Beast is said to be 666.

He did the calculation using Arabic numerals.

The Roman numeral V means 5 in English.

He is good at remembering consecutive numbers.