The renowned mathematician known for discovering the sum of the first $100$ natural numbers is

The famous German mathematician Carl Friedrich Gauss is famously known for quickly finding a method to sum the first $100$ natural numbers when he was just a young schoolboy.
He paired the numbers from opposite ends:

$$(1+100)=101,(2+99)=101,\dots ,(50+51)=101$$

Since there are $50$ such pairs, the total sum is:

$$50\times 101=5050$$

This led to the generalized formula for the sum of the first $n$ natural numbers:

$$S_n=\frac{n(n+1)}{2}$$