Then new forum moderation

[Vladimir Panteleev]

On Saturday, 22 September 2018 at 17:19:41 UTC, SashaGreat wrote:
> I did by head. But how a newbie would suppose to do that?

For that challenge, you only non-obvious thing need to know is 
the syntax for the modulus and ternary operators, which are 
present in many programming languages. You can do tthe 
calculation with a regular desktop calculator.

If that is too much, you can run the code on run.dlang.io. In 
this case, you only need to know how tocall a function and print 
its result.

If that is also too much, you can ask for help in the #d IRC 
channel.

The software suggests the above two options. In my opinion, it is 
a reasonable compromise, but I'm open to suggestions. (Note that 
at least once, a spammer managed to get through the CAPTCHA 
precisely by simply asking on #d, with a good samaritan providing 
the answer without inquiring further.)

> And by the way, after you do once why need to do every time?

It is needed to prevent flooding. However, successfully solving 
the CAPTCHA a number of times across a period of time while 
logged in will whitelist your account.