What if an evil genious says "Pick a box to fold up, if you pick the wrong one, i shall destroy earth!"
Think about it. You would want to be prepared right?
What if a criminal holds a gun to your head and says "If i have 16 apples, and i give 2 to Diana, and 14 to Richie, then richie gives 8 to Diana, who in turn gives me back 3, and i sell them for 6 apples. And the price of an apple is 0.23, and an orange is 0.47, how many Apples do I have?" You would need to know, or you would get shot.
This is what those teachers are prepping us for.
i dont think this really happens in everyday life ......=/..chances are reallllyy lil...