Question

$1+2+3+4+5+\cdots +27=$ ?

• A. 378
• B. 376
• C. 372
• D. 380

Answer 1

The correct option is A 378

The AP corresponding to the given series is 1, 2, 3,..., 27.

Sum of $n$ natural numbers is given by
$S_n$ = $\frac{n(n+1)}{2}.$

$\Rightarrow S_{27}=\frac{27(27+1)}{2}=\frac{27\times 28}{2}=27\times 14=378$