What is the largest five digit number which can be formed using the digits 7, 8, 5, 4 and 9, if the repetition of digits is not allowed?
Since we are required to form the largest 5 digit number, the leftmost digit at ten-thousands place will be the largest out of the 5 given digits, that is, 9.
Similarly, we can say,
Digit at thousands place = largest digit after 9 = 8
Digit at hundreds place = largest digit after 9 and 8 = 7
Digit at tens place = largest digit after 9, 8 and 7 = 5
Digit at ones place = remaining digit = 4
Placing the digits at their respective places, we get 98754.