Question

how many 4 digit numbers can be made using 9987? (using permutation rule)

Answer 1

The biggest 4 digit number you can think of, assuming integers, is 9999and the smallest is 1000, subtracting them, and adding one, will show us all 4 digit numbers. Originally Answered: How many numbers in all do we have with 4 digits? So, the number of four digit numbers = 9999–1000+1 = 9000such numbers!

Answer 2

digits-9,9,8,7

since 9 is two times so we considered only 1

now the answer will be-

$\frac{4!}{2!} \\ \frac{4 \times 3 \times 2}{2} \\ 12 \: numbers$
only 12 4 digit no. can be formed (diffrent)