Answer:
The largest 7-digit number, is a 7 nine digits, this number is:
9,999,999
If we subtract one, we get a 7-digit number smaller than this one.
if we add one, we get an 8-digit number.
Then this one is the greatest 7-digit number.
The successor of this number, is equal to the number plus one:
9,999,999 + 1 = 10,000,000
The smallest 8-digit number is the first 8-digit number, and we know that this one is:
10,000,000
And the predecessor is equal to this number minus one:
10,000,000 - 1 = 9,999,999
So we can conclude that:
The successor of the greatest 7-digit is the smallest 8-digit number
The predecessor of the smallest 8-digit number is the greatest 7-digit number.
And we could interpolate this for any N-digit number, such that:
The successor of the greatest N-digit is the smallest (N + 1)-digit number
The predecessor of the smallest (N + 1)-digit number is the greatest N-digit number.
