Answer:
6750
Explanation:
The first four-digit number divisible by 4 is 1000.
The last four-digit number divisible by 4 is 9996.
Modeling this as an arithmetic sequence, the nth term is:
a = 1000 + 4(n − 1)
So the number of terms is:
9996 = 1000 + 4(n − 1)
8996 = 4(n − 1)
2249 = n − 1
n = 2250
There are 2250 four-digit numbers that are divisible by 4. Since there are a total of 9000 four-digit numbers, that means there are 6750 four-digit numbers that are NOT divisible by 4.