easy as 1-2-3

Easy as 1-2-3 is an idiom which is describing something that is incredibly easy. This phrase expressed how simple a task is to complete due to the simplicity of learning your numbers 1, 2 and 3. Learning numbers 1, 2 and 3 are one of the first things a young child will learn and often the easiest to remember. Therefore, when this phrase is used about something you are asked to do or have already done, it means it was very easy to do.