Question

$\infty 1 + 2 + 3 + 4 + 5 +$
​

Answer 1

The answer is infinity or if x=the number at the end it is (x+1)*x/2

Answer 2

$1 + 2 + 3 + 4 + 5 + ............ \infty$

We know that;

$\color{blue}\boxed{S_{n}=\frac{n}{2}[2a+(n-1)d]}$

Where;

• $S_{n}$ is sum of n terms.
• n is number of trems.
• a is the 1st term.
• d is common difference.

$\implies S_{n}=\frac{n}{2}[2(1)+(n-1)(1)]$

$\implies S_{n}=\frac{n}{2}[2+n - 1]$

THEREFORE,sum of natural numbers upto infinity is:

$\therefore \color{orange} \boxed{ S_{n}=\frac{n(n + 1)}{2}}$

HOPE THAT HELPS!!!