Use of mathematics in everyday life?

Answer 1

• In business, when you calculate profits, etc.
• When you buy from a store and you check your change.
• When you see a penny by the street, put it in your wallet and start calculating how much money you have.
• [If you're an athlete] When you have a pedometer and you want to measure how many steps you take per unit of time.
• [If you're just curious] To check the actual density of water your cup can hold.

and many more...