It is not, so there can be no reason.
It is 1,000.
The smallest 5 digit odd number is: 10001 The greatest 4 digit even number is: 9998 Subtracting 9998 from 10001 gives you 3.
It is not. 1000 is, so the question is nonsensical.
It is 9998, or if the digits can't be repeated, it is 9876.
9998
It is: 9998
9998
9998
9998
It is an even number because it is divisible by 2 with no remainder
The largest 4-digit even number is 9,998.
1