A k equals 0. 1 10,000, and 639k is 639,000.
Simplified Chinese character "Wan" and traditional Chinese character (hereinafter referred to as "_") are originally two different glyphs. _ It was first seen in Oracle Bone Inscriptions in Shang Dynasty. It is shaped like a scorpion. Later, the pictophonetic word "mi" was created to express the original meaning of "_", and 10 thousand is a numeral, so 10 thousand also refers to a large number. "Wan" also began to appear in Oracle Bone Inscriptions. The original intention is unknown, and it was still used as a quantifier during the Spring and Autumn Period and the Warring States Period. In this sense, it is a synonym for "_".