Question

1+2+3+....................+100​

Answer 1

Answer:

sum of natural numbers upto n = n(n+1)/2

here n=100

1+2+3+..........+100 = 100(100+1)/2

                            = 5050

Answer 2

Answer:

a=1

d=2-1

=1

a*n=100

a+(n-1)d=100

=>1+(n-1)1=100

=>1+n-1=100

=>n=100

Hope it helps☺