Originally Posted by

**Soroban** Hello, ezwind72!

These are not combinations!

With a password, the __order__ of the characters is important.

The first must be a letter: 26 choices.

The last must be a digit: 10 choices.

The others must be a letter __or__ a digit: 36 choices.

$\displaystyle \begin{array}{c|c} \text{Length} & \text{Choices} \\ \hline

2 & 26\cdot10 \\ 3 & 26\cdot36\cdot10 \\ 4 & 26\cdot36\cdot36\cdot10

\\ 5 & 26\cdot36\cdot36\cdot36\cdot10 \\

6 & 26\cdot36\cdot36\cdot36\cdot36\cdot10 \end{array}$

Total: .$\displaystyle 260 + 260\cdot36 + 260\cdot36^2 + 260\cdot36^3 + 260\cdot36^4 $

. . $\displaystyle = \;260\left(1 + 36 + 36^2 + 36^3 + 36^4\right) \;=\;260\,\frac{36^5-1}{36-1}$

. . $\displaystyle =\;260\,(1,\!727,\!605) \;=\;\boxed{449,\!177,\!300} $