To make the greatest number we start to fill the columns with higher to lower values, like we will fill digit 9 first then digit 8 and so on. So by following this rule, in the first column we will have digit 9, in the second column we already have number 6, then in third column we will place digit 8 and in the last column we will enter number 7. Look at the diagram below to understand this:
Hence, the greatest 4-digit number is 9,687 after applying all the conditions.
Now let us make lowest value 4-digit number. The process will remain same but to make the lowest number we will fill the columns from lower to higher digit values. So in the first column we will put 1, placing 0 will make this a 3-digit number. Now in third column we will place zero then in the last column we will place two, as shown in the below picture:
Hence, the greatest 4-digit number is 9,687 and the lowest is 1,602.