Answer:
5789
Step-by-step explanation:
There are 9 numbers with 1 digit (1-9).
There are 90 numbers with 2 digits (10-99).
There are 900 numbers with 3 digits (100-999).
There are 725 numbers with 4 digits (1000-1724).
So the total number of digits is:
(9)(1) + (90)(2) + (900)(3) + (725)(4) = 5789
