If radio station call letters must begin with either k or w and must include either two or three additional letters, how many different possibilities are there?

In this question, the condition that has to be met is:: 1. first letter k or w 2. the additional letter is 2 or 3

To answer this question, it is easier to group the possibilities by the additional letter, then add them together.

The additional letter is 2 First letter possibilities is 2 (k or w), then two additional of 26 letter. Then the calculation would be: 2 * 26 * 26 = 1352

The additional letter is 3 First letter possibilities is 2 (k or w), then three additional of 26 letter. Then the calculation would be: 2 * 26 * 26 * 26 = 35152

If you add them together, the result would be: 35152+1352 = 36504 possibilities