Where do our mathematical concepts come from? What part of these mathematical concepts consists in universal intuitions, shared by all human beings, and what part relies on specific tools, transmitted through culture and education? I will present research probing our ‘number sense’, a capacity to perceive and manipulate numbers that is present very early in life, and is shared with many non-human species. Our number sense however has limitations when compared to mathematical number concepts. I will then discuss how culture-specific tools, such as words or counting procedures, contribute to forge the concepts of number we routinely use.