Question

How many four digit no. can be formed by using the digits 1,2,4,5,7,8,9 if repetition is allowed?​

Answer 1

Answer:

there will be possibilities of 28 .

Step-by-step explanation:

we have 1245789 if we shortly do we have

7 numbers at all nd we have to make 4 digits then multiply the 7×4 we get 28.

But if u wanna do in long term method ,

then make 4 pairs digit numbers to get 28 times..