The biggest 4 digit number that can be made from using the digits of 850236, using a digit at most once, is 8653.
-4790281
The largest numeral that can be formed using all 10 digits is 9876543210. This number contains all the digits from 0 to 9 in descending order, making it the largest possible arrangement. Any other arrangement would result in a smaller number.
Assuming each digit only once: 65432 (and no further mathematical operations).
It is: 63,477
8,754,321
8643
531
The biggest 4 digit number that can be made from using the digits of 850236, using a digit at most once, is 8653.
9531
-4790281
3201
9876543210
9+3-1
972.
Using those three digits it is 145.
Assuming each digit only once: 65432 (and no further mathematical operations).