Make the greatest 4 digit number by using any one digit twice from the following digits
3, 8, 7

The correct answer is 8873

To make the greatest number, let us first arrange the numbers in descending order.
⇒ 8, 7, 3
Since it is required to make a 4 digit number, we need to take the biggest digit and use it twice i. e. 8 in this case.
⇒ 8, 8, 7, 3 and the number is 8873