# The value of one atomic mass unit

In my textbook, it is given:

1 atomic mass unit equals $1/12$th mass of one carbon 12-atom. Since mass of $6.02 * 10^{26}$ atoms of carbon-12 is $12\space\text{kg}$. Thus,

$$1 \text{ a.m.u (or u)} = \frac{1}{12} * \frac{12}{6.02 * 10^{26}} \text{ kg}$$

This makes sense to me. But what follows is that they make this value equal to:

$$1.66 * 10^{-27} \text{ kg}$$

Which goes against the value that I had thought. I thought that the $12$s would cancel out resulting in only:

$$(6.02*10^{26})^{-1} \text{ kg}$$

Please help my out in figuring where did I go wrong.

• $1.66\times 10^{-27} = (6.02\times 10^{26})^{-1}$ :-D – Steve Byrnes Mar 28 '14 at 12:32
• @SteveB That is an answer in itself. Why don't you post it as such? – Emilio Pisanty Mar 28 '14 at 12:35

## 1 Answer

Both your answers are same.

$1.66\times 10^{-27} = (6.02\times 10^{26})^{-1}$

Hope that helps...

• Oh ! Why didn't I think of it .... Thanks anyway. – Gaurang Tandon Mar 28 '14 at 13:05