Answer: The required sum of the terms is 36.
Step-by-step explanation: We are given that the following series has six terms :
1 + 3 + 5 + . . . + 11.
We are to find the sum of the terms of the series.
We see the following pattern in the consecutive terms of the series :

So, the given series is an ARITHMETIC series with fist term 1 and common difference 2.
We know that
the sum of first n terms of an arithmetic series with first term a and common difference d is given by

For the given series,
first term, a = 1 and common difference, d = 2.
Therefore, the sum of first six terms will be

Thus, the required sum of the terms is 36.