Question

Find the sum of the numbers between 10 and 30​

Answer 1

the sum of the numbers between 10 & 30 =

11+12+.............................+29+30

= 410

Answer 2

Answer:

380

Step-by-step explanation:

Given :

To find the sum of the natural numbers between 10 and 30.

Solution :

We know that,

Sum of numbers in an A.P

$S_n = \frac{n}{2}(a + l)$

Here $S_n$ - meant the sum of the n terms of an A.P

n - meant the number of terms,

Here, since they are natural numbers, there common difference is 1,

and hence, $n = \frac{l-a}{d} +1 = \frac{29 - 11}{1} +1 = 19$

a - meant the first term, i.e., 11

l - meant the last term, i.e., 29

By applying the formula,

We get,

$S_n = \frac{19}{2}(29+11)$

$S_n = \frac{19}{2}(40)$

$S_n = 19(20)$

$S_n = 380$

∴ The sum of numbers between 10 an 30 i.e., 11 to 29 = 11 + 12 + 13 +...+ 29 = 380