Question

write the sum using sigma notation:
$1 + 2 + 3 + 4 + \cdots + 124 = \sum\limits_{n=1}^{a} b$, where

$a = \square$

$b = \square$

Explanation:

Step1: Identify upper limit A

The sum ends at 124, so this is the upper index of the sigma notation.
$A = 124$

Step2: Identify term B

The terms are consecutive positive integers starting at 1, so the general term is the index variable $n$.
$B = n$

Answer:

$A = 124$
$B = n$