Why are indians steryotyped to be good at maths and computers?

I mean the south asian indians. Do people have the wrong asians because I've never seen an indians that is extreamly good at maths or at using computers and they are supposed to be bad at sport I think this because there is very few sports figures that are of south east asian decsent I can only think of one amir khan but they are suppised to be bad at sport mostlt every indian I met they are mostly bangladesh they can run real fast and when I went bangladesh that is were I'm from every teenager there around my age (15) they are extreamly strong athletic body and can run forever and with speed why is the steryotype that they are good at math and computers?