A while back, Wordpress introduced an annoying little feature, where you have to solve a simple math question in order to log in to your site:
I ignored this for a while, but decided it was too much of a hassle wile offering no real benefit. However, finding a way to disable it is not very intuitive, as it is not actually a core Wordpress feature, but rather one added with Jetpack. It's part of the Protect module:
Disabling Protect disables the captcha.
If you don't see it on the main Jetpack page, click on the "See all xx Jetpack features" button:
and search for it:
After disabling, you'll no longer get asked any nagging math questions on login:
PLEASE NOTE: Disabling this feature may decrease security for your site. Use your best judgement!