Hi

No, after 12th by just passing maths additionally, you won't be  eligible for jee main.

This is because,

To be eligible for jee main, you should have studied and passed Maths in your 12th board examination itself as a compulsory subject.

Passing maths later on additionally after 12th won't make you eligible .

For your reference,

Jee main eligibility criteria is given below-

---------------------------) Qualification required :- to be eligible  for JEE mains you need 10+2/equivalent qualification from a recognised board.

-------------------------) Passing year :- one is eligible for JEE main examination for consecutive three years starting from the year of appearing for 12th /equivalent examination i. e to be eligible  for JEE mains 2022 you should be either appearing for 12th board exam or equivalent  in 2022 or should have passed it in 2021 or 2020

-------------------------) There is no age limit to be eligible

-------------------------) there is no minimum percentage requirement to be eligible for JEE Main for BE /Btech.

But yes,

To be eligible for BE/BTech  in NITs, IIITs, CFTIs one needs at least 75% marks in class 12th if belongs to General or OBC category  or at least 65% marks in class 12th if belongs to Sc or St category or needs to be in top 20 percentile of their board examination.

IMPORTANT NOTE :-  This minimum percentage barrier of 75 % - 65% for NITs, IIITs, CFTIs  has been lifted off for jee main 2022 . It means to be eligible all you need to be eligible is to have at least passed 12th .

For detailed information about jee main eligibility criteria  go through our page, the link for which is provided below

https://engineering.careers360.com/articles/jee-main-eligibility-criteria

Thank you