The main group number for an element can be found from its column on the periodic table. For example, carbon is in group 4 and has 4 valence electrons. Oxygen is in group 6 and has 6 valence electrons.
VRAM or (video RAM), reference to any type of random access memory (RAM) is a dual-ported variant of dynamic RAM (DRAM) used to store the framebuffer in graphics adapters.