`10p_r = 720`

If ""^(10)P_(r) = 720, find r.

If .^(n)P_(r) = 720 and .^(n)C_(r) = 120 , then find r. = (5 xx 4 xx 3)/(3 xx 2 xx1) xx (4xx 3 xx 2)/(3 xx 2xx1) = 10 xx 4 = 40 .

Find 'r' when : (i) ""^(10)P_(r )=2 ""^(9)P_(r ) (ii) ""^(11)P_(r )= ""^(12)P_(r-1) .

If .^(n)P_(r)=720 and .^(n)C_(r)=120 then find the value of r.

Find r if : ^10P_r=2. ^9P_r

If ^(10)P_(r)=5040, find the value of r

Find the Number Series 720, 180, 176, 44, 40, 10, ?, ?

(i) If ""^(15)P_(r)=2730, find the value of r. (ii) If ""^(10)P_(r)=5040, find the value of r.