Answer: 120
Step-by-step explanation:
The given digits : 9, 8, 7, 5, 3, 1
Number of digits : 6
If repetition of digit is not allowed then we use permutations.
We know that the number of permutations of n things taking r at a time is given by :-
[tex]^nP_r=\dfrac{n!}{(n-r)!}[/tex]
Now, the number of permutations of 6 digits taking 3 at a time is given by :-
[tex]^6P_3=\dfrac{6!}{(6-3)!}\\\\=\dfrac{6\times5\times4\times3!}{3!}=120[/tex]
