2. Infinity

The quest to figure out infinite numbers began with Zeno's paradoxes, which also had an impact on Greek views of the universe, and during the Middle Ages, it was forbidden to study infinite numbers due to a ban imposed on Christianity but eventually, infinite numbers were revealed mathematically.

3. Equation

Equation began with solving real problems in everyday life and gave remarkably accurate predictions for what may appear to be complex and complicated phenomenon.

4. Zero

Zero is a number that was inconceivable to humankind and peculiar in many regards compared to the other numbers. Today, the existence of zero is common knowledge and most people find it hard to understand why it could be different or special.

5. i

Stephen Hawking and Roger Penrose use this number when explaining the origins of the universe. An imaginary number became a target of criticism among numerous mathematicians and was widely ridiculed during the mid-20th century.