xPath - sum(//*) explained

Question

Lets say we have the following XML structure:

<a><b>2<d>4</d></b><c>3</c></a> 

Why does sum(//*) return 274?

Answer 1

Because it's 243 + 24 + 3 + 4 = 274

//* means all elements, which are a, b, c, and d. Then, we summarize their text values, which include everything except tags.

I think, what you're looking for is sum(//*/text()), which is 9 in this case