For example, if cell A1=1, I want to run Macro1 once. If cell A1=2, I want
to run Macro2 once. If cell A1=3, do nothing.

I am familiar with Excel If/Then statements, so to my thinking, it would
look something like:

IF(A1=1,Run Macro1,IF(A1=2,Run Macro2,""))

I just don't know what the command is to "Run" the macro.