Question

What is the largest five digit number which can be formed using the digits 7, 8, 5, 4 and 9, if only one digit can be repeated? (2 marks)

Answer 1

Since we are required to form the largest 5 digit number, the leftmost digit at ten-thousand's place will be the largest out of the 5 given digits, that is, 9.
Since one digit can be repeated, we choose the largest number 9 as the repeating digit.
Thus, digit at thousand's place = 9 (0.5 marks)

Similarly, we can say,
Digit at hundred's place = largest digit after 9 =8
Digit at tens' place = largest digit after 9 and 8 = 7
Digit at ones' place = largest digit after 9, 8 and 7 = 5

Placing the digits at their respective places we get 99875. (1.5 marks)