Compound properties such as source text cannot be looped since they are temporally not consistent - you could style your text differently at every keyframe. What you want to do requires to use text animators or a source text expression. Either you type in the whole block of numbers and reveal each line with a text animtor or dynamically generate the numbers using string processing in the expression.
You'll want to pre-compose your animated text, Trim the Pre-comp in it's comp settings to the end if the animation, then in the Main Comp apply Time remapping to the nested pre-comp. When you have applied time remapping you go to the last keyframe, move the CTI back one frame, insert a new keyframe, then add this expression to Time Remapping to give you a perfect loop:
You also need to be aware that the speed of a text roll or crawl (roll is vertical movement, crawl is horizontal) is extremely important and should be controlled with an expression that matches the movement to the frame rate so that you don't end up with juddering unreadable text. See this article from the FAQ section of this forum for some good advice:FAQ: Why does horizontal motion stutter (judder) in my movies, such as during pans?
Both Thank you for the posting. I would prefer Animator and just have a block of numbers and then make each line appear, but I can not figure that out. Any help on that. Thanks again
A complex expression that I can't write off the top of my head. I'm still not exactly sure what your animation will look like. Is it a single line of changing text that is rolling or crawling or is it a bunch of lines of text that are being added to the screen one at a time?
Its not a crawl. The Animation is this I have a block of text
I want each row to appear with each keyframe So Keyframe one 3483 Keyframe two 7453...etc Then I want that to loop.
Can you explain in more detail how your result should look like?
You can create scrolling blocks of random numbers with the Random Text Block Shifting iExpression:
This sample image scrolls right to left and uses letters, but you can easily change this to use numbers and scroll from top to bottom.
Then I recommend Rick's solution with creating a precomp and time remapping it.