Four-digit numbers are 1000,1001,...,9999
Total number of four digit numbers are 9000.
Now,
54=2×33
So, for getting gcd with 2, we must have numbers multiple of 2 but not of 3.
Multiple of 2 are 1000,1002,.....,9998
Let total numbers be m, then
9998=1000+(m−1)2
⇒m=4500
Total numbers are 4500.
Multiple of 6 are 1002,1008....,9996
Let total numbers be n, then
9996=1002+(n−1)6
⇒n=1500
So, required number is =4500−1500=3000