+870 You mean the number pi π ? According to Wikipedia, it first appeared in a parchment written by the Egyptian scribe Ahmes, dating from the 16th century BC. But the notation π appeared only on the 18th century. It was choosen because π was the first letter of περιμετρος, which stands for "perimeter" in Greek, the number π being the ratio of the perimeter of circle (also known as the circumference) and its diameter.
+870 You mean the number pi π ? According to Wikipedia, it first appeared in a parchment written by the Egyptian scribe Ahmes, dating from the 16th century BC. But the notation π appeared only on the 18th century. It was choosen because π was the first letter of περιμετρος, which stands for "perimeter" in Greek, the number π being the ratio of the perimeter of circle (also known as the circumference) and its diameter.
