Question

The number of 5 digits telephone number having one of the digits repeated is?(0 can be the starting digit of number)

Answer 1

exactly one repeated, or at least one repeated?

Answer 2

exactly one repeated.

Answer 3

also please solve it with atleast one repeated.

Answer 4

60 way

Answer 5

at least one repeated would be equal to the total number minus the number with no repeats, which would be \[10^5-\frac{10!}{5!}\]

Answer 6

thanks...!