Simply.
It looks like this:
Short no and Example are static auto fill (10 and 1503 are the most common so they auto fill)
But Long no cant be auto filled like that. As you can see Long no has to be somethimes copied and pasted which is problematic.
My idea is for New record to auto fill from last known record. In this example autofill Long no from record 6 with 986656551.
Like this:
Obviously if there were other no in record 6 auto fill should look differently.
I hope I made myself clear.