15 points were marked on the straight line. How many segments were there in total, the ends of which are these points?

The solution of the problem:
We can draw a picture and mark points on it to make it clearer.
If we mark 15 points on a straight line, we begin to count the segments. 1 and 2 points – 1 segment, 2 and 3 points – 2 segments, and so on. We count to the end, we get 14 segments, because each point consists of 2 segments except the first and the last.
Answer: 14 segments.