How to add math captcha to WordPress Contact Form 7
Copy and paste it into WordPress Contact Form 7 form editor:
[quiz quiz-100 class:form-control "1+1=|2" "1+2=|3" "1+3=|4" "1+4=|5" "1+5=|6" "1+6=|7" "1+7=|8" "1+8=|9" "2+1=|3" "2+2=|4" "2+3=|5" "2+4=|6" "2+5=|7" "2+6=|8" "2+7=|9" "3+1=|4" "3+2=|5" "3+3=|6" "3+4=|7" "3+5=|8" "3+6=|9" "4+1=|5" "4+2=|6" "4+3=|7" "4+4=|8" "4+5=|9" "5+1=|6" "5+2=|7" "5+3=|8" "5+4=|9" "6+1=|7" "6+2=|8" "6+3=|9" "7+1=|8" "7+2=|9" "8+1=|9"]