Stirling's approximation, an Uncommon card

The card carries these facts from its Wikipedia article.

• It is a good approximation, leading to accurate results even for small values of n.
• It is named after James Stirling, though a related but less precise result was first stated by Abraham de Moivre.
• One way of stating the approximation involves the logarithm of the factorial: ln ⁡ n ! = n ln ⁡ n − n + O, where the big O notation means that, for all sufficiently large values of n, the difference between ln ⁡ n ! and n ln ⁡ n − n will be at most proportional to the logarithm of n.

Rarity in WikiCards follows a year of Wikipedia page views: the most read articles become Epic and Legendary cards. The Stirling's approximation article was read about 190,000 times in a year. ATK comes from the length of the article and DEF from its quality, so this card hits with 71 and blocks with 53: each hit it takes is cut by 21 %.

Open packs. Each pack holds five cards drawn from real Wikipedia articles, the rarest last, and the fifth card is always Rare or better. The odds are shown in the game. A free pack arrives every hour and two can wait, and the Coins you win in duels buy more packs.

The cards just above and just below Stirling's approximation in the power ranking, all domains together.