Question

Given that 1+2+3+.. +9 = 45, find the value of (11+12+13+..+19)

Answer 1

the answer is one hundred and thirty five

Answer 2

Given:

1+2+3+...+9= 45

To find:

11+12+13+....+19

Solution:

We can find the sum by following a simple process-

We know that both the series form an arithmetic progression with a common difference of 1.

The sum can be found by using the formula of summation.

Sum=n/2×(2a+(n-1)d)

Here n is the number of terms, a is the first term and d is the common difference of the series.

So, n=9; a=11; d=1

Putting the values in the formula,

Sum=9/2×(2×11+8×1)

=9/2×(22+8)

=9/2×30

=9×15

=135

Therefore, the value of 11+12+13+....+19 is 135.