Assuming you don't include numbers like 0673, then there are 9000 - all the numbers from 1000 to 9999. (It's not 8999 as one might expect, because the calculation requires the inclusivedifference.)
It is 1,000.
1000
There are 504 such numbers.
100,000
823543
5295
It is 1,000.
100000000000 kantutan
9000
1000
There are 504 such numbers.
100,000
9999
The question to help my son with his homework is: How many unique numbers can be formed by combining three sets of three digital decimal numbers
840
823543
There are 60480 numbers.