Answer:
<h2>Check the explanation.</h2>
Step-by-step explanation:
The highest four digit number is 9999 and lowest 4 digit number is 1000. The difference between them is (9999 - 1000) = 8999.
8999 cannot be difference according to the question, as here all the digits should be distinct rather than 0.
The difference between the 9 and 1 is 8, which is the highest difference among the unit digits rather than 0.
The 2nd lowest number after 9 is 8 and the 2nd highest unit digit after 1 is 2.
(8 - 2) = 6.
The difference will be highest if difference is calculated between the highest and lowest number.
With the 4 digits, 9, 8, 2, 1 the lowest number is 1289 and the highest number is 9821.
The difference is (9821 - 1289) = 8532.
