Nowadays, a lot of people are too dependent on calculators. Maybe because when they were young, they find math boring. We just need to teach our kids interesting and fun way in dealing with math. Math can be fun especially when you look at math in a completely different way.
You may want to let them try and work out how long it will take you to travel somewhere when you get in the car, by telling them what speed you'll be traveling and how far away your destination is.