Question

Write the greatest $7$ digit number having:

Four different digits

Answer 1

Numbers:

Greatest $7$ digits number$=9999999$

This number consists of only one but the greatest digit i.e $9$

To make the greatest number with four different digits it must consist of the greatest digits other than $9$

Three Greatest digits other than $9$$=8,7,6$

Thus,

Smallest $7digit$ number with four different digits $=9999876$