no it is not necessary until and unless you want to study math, if you are interested to pursue further in future in math domain or like the mathematics subject then you can take it otherwise there is no rule as such. It's totally up to your convenience.

HELLO,

Whether to choose mathematics in class 11th depends which stream you choose and on your future goals , as if you want to pursue Engineering courses or want to do course like Bcom Hons / Financing courses then you have to choose mathematics as it will be compulsory in future when you go for college admissions.

So first decide what you want to do in future , in which field you want to go as per that you have to choose , like if you want to pursue courses in which mathematics is compulsory then you have to choose mathematics in class 11th , but if you don't want to study mathematics or it is not required in your future study plans then you can continue without mathematics in class 11th.

Hope this will help!