Answer:The number should be 123456789.
Step-by-step explanation:
The total digits should be 9 i.e. 1, 2, 3, 4,5, 6,7, 8, and 9.
The largest number should be at the unit place, the 2nd largest number should be at the tenth place, and the 3rd largest number should be at the 100th place, and so on.
So in this way, the 1 number should be written at the left-most position.
Therefore we can conclude that The number should be 123456789.