HP - 951 Ink Cartridge - Magenta

It depends on the amount of color you are printing. These inks are changed individually, so you don't have to throw away the cyan and yellow if your magenta is used up. I am finding myself only changing the cartridges once or twice a year.

Magenta is a cross between red and purple. The bolder the colors the more purple it would look, the lighter the colors the more pink it looks. If they just put color that would be to easy for us. Mixing the colors will give you all the colors that you need, well for me it did. i hope I helped.