" ii) If "^(n)P_(4)=1680," find "n

If ""^(n)P_(4)=210 , find n.

If P(n,4)=1680 then find n=

If ^(n)P_(4)=360, find the value of n

(i) If n(A)=4, find n[P(A)] (ii) If n(A)=0, find n[P(A)] (iii) If n[P(A)]=256, find n (A)

If ""^((n-1))P_(3):""^(n)P_(4)=1:10 , find n.

If ""^(n-1)P_(3): ""^(n)P_(4)=1:9 find n.

(i) If ""^(n)P_(5)=20xx""^(n)P_(3) , find n. (ii) If 16xx""^(n)P_(3)=13xx""^(n+1)P_(3) , find n. (iii) If ""^(2n)P_(3)=100xx""^(n)P_(2) , find n.

If (""^(n+2)C_(7))/ (""^(n-1)P_(4) )=11/42 , find n.

13. If P(n-1,2):P(n,4)=1:9, find n