*Trick: To find the greatest number arrange the given numbers in descending order and to get the smallest number arrange the given digits in ascending order.

On using the digits: 6, 2, 7, 4 and 3 and only once, we get,

Greatest number = 76432

Smallest number = 23467

Now, the difference between the greatest and the least number = 76432 – 23467 = 52965