What should come in place of '?' in the given series?
34   58   106   202   394   ?

The correct answer is 778.

To find the missing number in the given series, let us analyze the pattern or difference between consecutive terms:

First term = 34
Second term = 58
Third term = 106
Fourth term = 202
Fifth term = 394

Let us look at the relationship between each consecutive pair of numbers:

$34\times 2-10=68-10=58$

$58\times 2-10=116-10=106$

$106\times 2-10=212-10=202$

$202\times 2-10=404-10=394$

Following the same pattern, to get the missing term ('?'):

$394\times 2-10=788-10=778$

Alternatively, looking at the differences between adjacent terms:
58 - 34 = 24
106 - 58 = 48 (24 × 2)
202 - 106 = 96 (48 × 2)
394 - 202 = 192 (96 × 2)

The next difference should be:
192 × 2 = 384

Adding 384 to the last term gives:
$394+384=778$

Thus, the number that comes in place of '?' is 778.