The sums of arithmetic sequence of 1+2+3+4 ... + 49

I'm sorry but I haven't learned this. Using what I do know, shouldn't it be infinity?

1225 is the sum of that arithmetic progression.

Step-by-step explanation:

Here 'a' is taken as the first term

And 'l' is taken as the last term

Sum of n = n / 2 (a + l)

= 49 / 2 (1 + 49)

= 49/2 * 50

= 49 x 25

= 1225