Dear Candidate,

We have to form natural numbers less than 7000. Means overall we have 4 places to fill.

1-  2-  3-   4-

Now clearly , on the first place we can't put 7 and 9, otherwise the number becames greater than 7000.

So, the first place can have digits from 0, 1 and 3 . Means it can be filled in 3 ways.

Now the second place can be filled in any 5 ways and similarly the 3rd and 4th place can be filled in 5 ways ecah because the repeatation is allowed.

So total possible natural numbers will be =

3*5*5*5 = 375

Hope this helps.