Question

11+12+13+14+15...+68+69+70

Answer 1

$\huge\mathtt\pink{Answer}$

$11+12+13+14+15+68+69+70$

$=23+13+14+15+68+69+70$

$=36+14+15+68+69+70$

$=50+15+68+69+70$

$=65+68+69+70$

$=133+69+70$

$=202+70$

$=272$

$\sf\green{hope \ it's \ helps \ you}$

Answer 2

Answer:

2430 is the answer

This given series is in AP i.e there is a common difference of 1 between two consecutive numbers.

Step-by-step explanation:

Thus to have its sum we will use formula

Sn=n/2(a+an)

over here n is no of terms a is the first term and an is the last term

a is already given in the question = 11

an is also given = 70

common difference = 1

Lets find no of terms in this series=

a + (n-1)d=an

11+(n-1)1=70

n= 60

sum = n/2(a+an)

60/2(11+70)

30*81

2430 ans..