There is a concept in science and engineering called significant digits. For example, if you are weighing something with a scale that can have an error of one pound or greater, the reading on the scale of tenths of pounds is really meaningless.
Whenever I encounter PI in my engineering work I will try control the related phenomenon with parts that have a possible error of +/-15%. Hence, the only significant digit of PI is the “3”, not the digits to the right of the decimal point, which affect the accuracy by less than 5%.