If you're identifying color for pretty much anything digital, you're working in an RGB colorspace. If the project you're working on requires percentage representation, purple is made of 63% red, 13% green, and 94% blue.
If you're identifying color for a print project, you're most likely using a CMYK colorspace—the percentages are 33% cyan, 87% magenta, 0% yellow, 6% black.