What should come in place of the question mark (?) in the given series?
779 780 784 793 809 ?

The correct answer is 834.

To find the missing number in the given series, let us observe the pattern of differences between consecutive terms:

$780-779=1$

$784-780=4$

$793-784=9$

$809-793=16$

We can see that the differences between consecutive terms are consecutive perfect squares:
1 = 1²
4 = 2²
9 = 3²
16 = 4²

Following this pattern, the next difference must be 5² = 25.

To find the value of the question mark (?), add 25 to the last term of the series (809):

$?=809+25=834$

Thus, the number that comes in place of the question mark is 834.