Calculate the Sum of Numbers from 11 to 20: Simple Formula & Solution

The sum of the numbers from 11 to 20 is:

11 + 12 + 13 + 14 + 15 + 16 + 17 + 18 + 19 + 20

To find the sum, we can use the formula for the sum of an arithmetic series:

S = n/2 * (a + l)

Where S is the sum, n is the number of terms, a is the first term, and l is the last term.

In this case, a = 11, l = 20, and n = 10 (since there are 10 terms from 11 to 20).

Plugging in the values, we get:

S = 10/2 * (11 + 20) S = 10/2 * 31 S = 5 * 31 S = 155

Therefore, the sum of the numbers from 11 to 20 is 155.