Answer:
I suppose that this refers to numbers like:
N = abcd
Where a, b, c and d are single digits.
We want to find the number of 4-digit numbers such that:
a, b, c and d are even numbers.
So let's count the number of options for each digit, where we impose that the possible digits must be even.
a: Here we have the options {2, 4, 6, 8} ( 0 is an even digit, but if we take a = 0, then this would be a 3 digit number) Then we have 4 options for a.
b: Here we have the options {0, 2, 4, 6, 8}. 5 options in total.
c: Here we have the options {0, 2, 4, 6, 8}. 5 options in total.
d: Here we have the options {0, 2, 4, 6, 8}. 5 options in total.
The total number of possible combinations will be equal to the product of the number of options for each selection.
C = 4*5*5*5 = 500
There are 500 "nice" numbers of 4-digits.