You are from maths hons background and you are interested in MBA. To do MBA you will first have to clear various entrance exams like CAT, MAT, XAT, CMAT, NMAT etc and then if you meet the cutoff then you shall get admission in top institutes through it.

SO here are the Management exams listed and you can choose which to give but do not limit yourself in one or 2. 

MBA exams

Also you can know the notification dates of applications, result, exam etc on the link provided above.

You should also know pros and cons of each and if interested in Maths then you can choose Finance.

Rest you will have to decide.

Good Luck.