text: where do you use common factors in math in everyday life? greatest common factors and all that jazz maths in general are underrated in their use in everyday life.   when you go to the supermarket and compare prices of different sized packages you use common factors.  maths in school is taught in an isolated academic context. teachers (of which i am one) need to relate their subjects to relevant everyday contexts to show the value of the knowledge. when i was at school, i saw no value of calculus, then i discovered that it was very relevant in my trade.