How do i convert the US dollar to the japanese yen in my head?

Question:

And can you give me the eqivilents to our cents dollars bills and soforth

Answer:

The easiest way is to add two extra zeros.

While this is not the exact exchange rate, it will give you a rough idea of how much something is.

For example 1 dollar , add two extra zeros is 100yen.

In reality, 1 dollar is about 78 yen (bad exchange rate now).

So 100, quick head conversion would be 10000yen.
In reality it's about 7800yen.

Again it gives you a "rough" idea.

In the past, adding the two extra zeros was a good indicator because the dollar to yen exchange rate was about 1 to 100, but because the dollar is a bit weak right now and the yen strong, it's fluxed.

But again it gives you a good rough estimate if you need to do it all in your head without google, xe.com or a calculator.