Alright, let's go on to this problem,
an interesting problem.
"Bacteria that double every 24 hours
fill a lake it has infested
after precisely 60 days.
On what day was the lake half-full?"
Now, a lot of people see this problem
and they'd think, "30, like,
you know, you split it in half."
Well, that's not the right answer.
And also people might want a calculator.
It's too big, it's math, it's boring,
I don't want to do that either.
But if you do this problem backwards,
you get the answer right away.
What's the answer? 59, obviously.
You start at the end, you go backwards,
it's like, "Oh yeah,
it's half-full, the answer is 59."
Here's another puzzle,
a little bit more complicated.
You have six numbers, 1 through 6.
The cards are face down.
You and I are going to pick a card.
You pick a card and you look at it
and it says the number 2.
I look at my card,
I think about it for a minute
and I say, "I want to trade."
The reason I want to trade,