Replacing last 6 digits from a number

[smenaru]

I am looking to replace the last 6 digits from a number with 6 random numbers. How do I do that?
I have a bunch of text files and I want to make the software scan for all the 9 digits combinations and replace the last 6 ones randomly.

[smenaru]

The same number appears multiple times in the files. I want all of them to be edited the same.

For example: 624599153 appears 10 times in the file. I want to replace the last 6 digits in the same way for all 10 instances where this number appears. I hope I made myself clear.

[DigitalVolcano]

Currently there isn't a function in TextCrawler to replace with random text or numbers, sorry.