Plus, Minus, Divide

Using the sum of the first $n$ natural numbers formula ,

$\left(\dfrac{2\frac{n(n+1)}{2}}{n}\right)-n$

$\frac{n(n+1)}{n}-n$

$n+1-n=1$

$\large = \displaystyle \lim_{n\to\infty} \dfrac{\left(\displaystyle \sum_{j=1}^n 2j \right) - \left(\displaystyle \sum_{j=1}^n 1 \right)^2}{ \displaystyle \sum_{j=1}^n 1}$ $\large = \dfrac{2\dfrac{n(n+1)}{2} - n^2}{n}$

$\large = n + 1 - n = \boxed{1}$

When you see a problem that looks extremely hard but its like 30 points say 1.

I don't know sign mean but its like a simple algebraic expression j=1

then 2j =2

so it will be (2-1)/1=1