Why do some forums,

[pljames]

make it so hard to join them like, what's the capital of or fill in this line and such. I am a senior citizen and sometimes have memory loss and get confused by these questions. Paul

[k-pappy]

Spammers and bots love to use forums to promote wares.  The captcha is aimed at preventing that.

[DaveW]

Spammers and bots love to use forums to promote wares.  The captcha is aimed at preventing that.

Good answer.

They put stuff like that in there due to program robots that pretend to be people and join forums to advertize some product or service.  To answer a question like that requres that you can read and understand what is being asked - something a computer program cannot do. (at least not yet)