五 wǔ

五 wǔ is the numeral 5.

武当山 is Wǔ dāng shān where Wǔ dāng or Wu Tang Clan derived its name. Yes the character has the same sound but is written differently than the number 5. From Wiktionary, one possibility is that 五 was originally written as five horizontal lines, similar to 一, 二, 三, and the obsolete 亖 (“four”), but in common writing the lines would blend together. Thus, two lines were turned vertical and the right one was shortened, to form one stroke with the middle horizontal line. An alternate hypothesis is that 五 originally resembled 㐅 with a bar on top and a bar on bottom, as in 𠄡. This would have meant five because when counting on a single hand, one first counts to five and then crosses back the other way to ten.