Formation of the biggest and the smallest numbers
If 4 digits 4, 8, 5, 7 are given we can form twenty four four-digit numbers by using each of these digits only once.
Have a look-
4857, 4578, 4758, 4875, 4587, 4785,
5487, 5478, 5847, 5874, 5748, 5784,
7485, 7458, 7845, 7854, 7548, 7584,
8457, 8475, 8574, 8547, 8745, 8754.
From these numbers, to write the smallest number we should write smallest digit first and then remaining digits in ascending order i.e. the smallest number will be 4578.
To write the biggest number we should write largest digit first and then remaining digits in descending order so the biggest number from above numbers will be 8754.
If we have to form smallest five digit number by using these four digits,
We should write the smallest digit twice and remaining digits in ascending order so the smallest number will be 44578.
Similarly to form the biggest five digit number using these four digits, we should write the biggest digit twice and remaining digits in descending order.
So the biggest five digit number will be 88754.