He didnt explain it well enough.

He should of said this:

"How do you write down 1 dollar?"
"Umm... 1.00?"
"yes. Now how would you write down .002 dollars?"
"Umm .002?"
"yep. Now how do you write 1 cent?"
".01?"
"yea. Now how do you write .002 cents?"
".002?"
"No, you just said thats how you write .002 dollars."
"Oh... .00002?"
"there you go. Now multiply that by my kb"

Thats all he had to do. He made it WAY to confusing.