50. The ancient Greek mathematician Pythagoras discovered the secrets of "figurate numbers." He called $1,3,6,10,15, \cdots \ldots$ triangular numbers because these quantities of dots can be arranged into triangular arrays, as shown in the figure below. The 10th figure has $\qquad$ dots.

将上面的文本翻译成英文，请保留源文本的换行和格式，直接输出翻译结果。
answer: 55