Scale AI’s 27-year-old CEO, Alexandr Wang, used to compete in national high school math competitions. His latest math-related victory may have been convincing investors in Silicon Valley to stretch his own company’s numbers. The startup’s $13.8 billion valuation, from a billion-dollar round it raised in May, is almost certainly too high, whichever formula you use.The eight-year-old startup mostly handles the low-end work on artificial intelligence that large-language models developers like Alpha...