Question

How many integers from 4000 to 4999 have at least one of its digits repeated

Answer 1

There are 1000 number from 4000–4999 both inclusive. Unique numbers would be 9*8*7 (as 4 is already present in the thousands.)

Answer 2

There are 1000 of numbers from 4000 to 4999 that have at least one of its digits repeated.