Follow these steps:
Set the playhead at the beginning of the project
Add > Text Generators > Numbers
Animate checked
Start 0
End 1
Move the playhead forward 1 frame and type 'o' to set an out point
[I recommend going into Properties and reset transform so that it's centered in the canvas
I further recommend Format > Advanced Formatting > Monospace checked
Set the Basic Formatting > Alignment > Center
ITC Franklin Gothic will work well for this effect]
Select the Parent Group and type 'K' to clone the 2 frame group. Turn off the group in the layers list.
Type 'L' or click the replicator icon to create a replicator.
Set Replicator Controls:
Columns & Rows to arrange your numbers
Origin: Upper Left
Build Style: By Row
In Cell Controls:
Play Frames checked
Check Random Start Frame
Set Hold Frames to 7 (to start - you can adjust this later)
Set Hold Frames Random to 4 (to start - again - adjust to taste.)
If you have trouble with the animation showing consistently, you can select the Clone Layer and in Properties > Timing, set the End Condition to Loop and the End Duration to the length of the project.) Motion will usually "snap out of it" once it has a chance to render the animation though, just restart playback from the beginning of the project a few times.