Find the value of `1+2+3+....+n`.

Find the value of 2^(n){1.3.5.....(2n-3)(2n-1)}

Find the value of ( 1 - 1/3 ) ( 1 - 1/4 ) ( 1 - 1/5 ) ---------- ( 1 - 1/n ) is ( a ) 2/n ( b ) 4/n ( c ) 3/n ( d ) 5/n

Find the value of ( i^2 + n ) ( i^2 + n - 1 ) ( i^2 + n - 2 ) .......( i^2 + 1 )

Find the value of ( i^2 + 1 ) times ( i^2 + 2 ) times ( i^2 + 3 ) ------ ( i^2 + n )

Find the value of ( 2^(n+4) - 2 ( 2^n )) / ( 2(2^(n+3) )

Find the value of if n if "^(n+1)P_3 = 4^(n)P_2