Going both ways
Probably most of the world is bilingual, or more than bilingual. It is common in many countries to speak a national language alongside an international lingua franca such as Arabic, Spanish or English. On top of that, there may be a mother tongue that is not the same as a national language. A Nigerian, for instance, may be at once one of the million speakers of Berom, one of the 64 million speakers of Hausa and one of the 1.13 billion speakers of English. The same pattern is repeated across the globe.
