Question

what is the value of 1+2+3+4+5+.......+19 ? ​

Answer 1

Answer:

The value of1+2+3+4+5+.......+19=190

Answer 2

Answer:

the above seires are in a. p

whose ist term is a=1

and last term l=19

and common difference d=2-1=1

now find out the no of terms as shown below

l=a+(n-1)*d

19=1+(n-1)*1

18=n-1

n=18+1=19

now sum of series is

S=n/2(a+l)

=19*(1+19)/(2)

=19*20/(2)

=19*10

=190

therefore sum is 190