You don't need to. I remember when I was a child, our family have this tradition of walking around the park after dinner. My parents would talk about work and ask about my day. And sometimes my father would throw questions like "why do you think there are 60 minutes in an hour instead of say 57" "why is 1/3 = 0.33333... is there a possibility there's a digit of 4 down the road?". I'm not sure if he come up with these question randomly or he has a system, but I still remembers a lot of them today.