Adding Fractions · Superchallenge problem

A pattern of fractions starts $\dfrac{1}{10}, \dfrac{3}{10}, \dfrac{6}{10}, \dfrac{10}{10}, \dfrac{15}{10}, \ldots$ Each number is found by adding to the one before it: first $\dfrac{2}{10}$, then $\dfrac{3}{10}$, then $\dfrac{4}{10}$, and so on, adding one more tenth each time. What is the sum of the first eight numbers in the pattern?