Using numbers as markers on a graph.

Is it possible to, instead of using a shape as a marker, use a number? I need to number 4 different points on a graph.

Not directly, no; the markers are autoshapes only.

HOWEVER:
Chart Tools: Layout Ribbon => Labels Panel => Data Labels Dropdown: Center Option

This will label the marker point with the numerical value of the data point.
You can use "Format Selection: Series (n) Data Labels" to change it to use:
the Y value, X value, and/or Series Name
(although the way they are named in the popup will depend on what kind of chart you are using)

So if you turn the markers OFF and then turn the data labels ON, and then format them correctly, you might be able to get what you want.

Worked perfectly. Thanks!